The Glomerular Filtration Rate: From the Diagnosis of Kidney Function to a Public Health Tool.

The prevalence of chronic kidney disease (CKD) continues to increase worldwide, as well as the associated morbidity and mortality and the consequences on the patients' quality of life and countries' economies. CKD often evolves without being recognized by patients and physicians, although the diagnosis is based on two simple laboratory data: the estimated glomerular filtration rate (eGFR) and urine analysis. To measure GFR, the knowledge about the physiologic processes at the nephron level, the concept of clearance, and the identification of creatinine as a suitable endogenous marker for measuring the creatinine clearance (CrCl) had to be previously developed. On those bases, different equations to calculate CrCl (Cockcroft and Gault, 1976), or estimated GFR (four variables MDRD, 1999; CKD-Epi, 2009, among others) were generated. They all include creatinine and some demographic data, such as sex and age. However, to compare results throughout life or among laboratories, the creatinine determination must be standardized. In addition, the accuracy of these equations remains controversial in certain subgroups of patients. For these reasons, other mathematical models to improve CrCl estimation have been developed, such as when urine cannot be collected, in debilitated elderly patients and patients with trauma, diabetes, or obesity. Currently, eGFR in adults can be measured and reported immediately, using isotope dilution mass spectrometry traceable creatinine-based equations. In conclusion, based on knowledge obtained from renal physiology, eGFR can be used in the clinic for the diagnosis and early treatment of CKD, as well as a public instrument to estimate the prevalence.

Correlación entre las ecuaciones para la estimación del filtrado glomerular (MDRD, CKD-EPI,) y la depuración de creatinina en orina de 24 horas en pacientes oncológicos / Correlation between the equations for the estimation of the filtering glomerular (MDRD, CKD-EPI,) and creatinine clearance in 24-hour urine in cancer patients

Demostrar la correlación entre las ecuaciones MDRD, CKD-EPI con la depuración de creatinina de 24 horas en pacientes oncológicos. Estudio transversal realizado en el Instituto Oncológico Nacional Dr Juan Tanca Marengo durante el periodo de tiempo comprendido entre el mes de agosto 2019 a agosto de 2020. Al evaluar las distintas variable MDRD obtuvo un valor promedio de 44,81 ml/min/m2 con un intervalo de 41,07 ­ 48,55 ml/min/m2 , la variable CKD-EPI el valor promedio fue 43,59 + 18,09 ml/min/m2 con un intervalo de 40,01 ­ 47,18 ml/min/m2 , para el estándar de referencia depuración de creatinina de 24 horas el promedio fue de 54ml/min/m2 Al evaluar la relación entre los dos estimadores de TFG se encontró que ambos presentan una fiabilidad regular presentando una correlación intraclase de 0,43 (p<0,05) entre los estimadores CKD-EPI y MDRD en relación con la TFG de creatinina de 24horas. Cuando se evaluó pacientes con tumores sólidos y hematológicos, se encontró una mayor correlación intraclase con la escala MDRD-4 0,60 (0,25 ­ 0,82) < 0,05 en tumores hematológicos en comparación con CKD-EPI. En la población general, CKD-EPI es la fórmula recomendada, y se está recomendado con mayor frecuencia en pacientes oncológicos. Nuestro estudio demostró que la ecuación MDRD es la fórmula que mejor se correlaciona con la depuración de creatinina de 24 horas, siendo mejor en el grupo de tumores hematológicos, pero no existe diferencia estadísticamente significativa entre las dos ecuaciones.

To demonstrate the correlation between the MDRD, CKD-EPI equations with the 24-hour creatinine clearance in cancer patients. Cross-sectional study carried out at the National Oncological Institute Dr Juan Tanca Marengo during the period of time between the month of August 2019 to August 2020. When evaluating the different MDRD variables, an average value of 44.81 ml / min / m2 was obtained with an interval of 41.07 ­ 48.55 ml / min / m2, the CKD-EPI variable the average value was 43.59 + 18 , 09 ml / min / m2 with an interval of 40.01 ­ 47.18 ml / min / m2, for the reference standard creatinine clearance of 24 hours the average was 54 ml / min / m2 When evaluating the relationship between the two estimators of GFR, it was found that both present a regular reliability, presenting an intraclass correlation of 0.43 (p <0.05) between the CKD-EPI and MDRD estimators in relation to the 24-hour creatinine GFR. When patients with solid and hematological tumors were evaluated, a higher intraclass correlation was found with the MDRD-4 scale 0.60 (0.25 ­ 0.82) <0.05 in hematological tumors compared to CKD-EPI. In the general population, CKD-EPI is the recommended formulation, and it is more frequently recommended in cancer patients. Our study showed that the MDRD equation is the formula that best correlates with 24-hour creatinine clearance, being better in the group of hematological tumors, but there is no statistically significant difference between the two equations.

Comparación de las Fórmulas Cockcroft-Gault y Mdrd con la Depuración de la Creatinina Endógena para la Estimación de la Función Renal en Pacientes Adultos Ambulatorios Atendidos en un Hospital de Referencia Peruano / Comparison of the Cockcroft-Gault and Mdrd Equations With the Endogenous Creatinine Clearance to Estimate Renal Function in Ambulatory Adult Patients Treated in a Peruvian Reference Hospital

Resumen Introducción: La estimación de la función renal es un componente importante de laatención hospitalaria. Para ello, habitualmente, se utilizan estimaciones basadas en las cifras de creatinina sérica. Las fórmulas más utilizadas son la MDRD y Cockcroft-Gault.Objetivo:Evaluar la correlación de las ecuaciones de Cockcroft-Gault y MDRD con el valor de depuración de creatinina, basada en la recolección de orina de 24 horas. Material y métodos:Para realizar el estudio se utilizaron los registros del Servicio de Patología Clínica del HospitalNacional Hipólito Unanue, un hospital de referencia en Lima, Perú. La creatinina sérica se realizó mediante el método de Jaffe. La depuración de creatinina se llevó a cabo mediante las determinaciones simultáneas de creatinina sérica y creatinina urinaria, obtenida a través de la recolección de orina de 24 horas. Se calcularon las correlaciones utilizando el coeficiente de Pearson, considerando significativos valores de p<0.05. Resultados:Se incluyeron 426 pacientes. La edad promedio de la población estudiada fue de 58.36 +/- 16.21 años, con un mínimo de 15 años y un máximo de 91 años. Hubo un discreto predominio del género femenino (51.2%).La correlación entre la depuración de creatinina y aquella estimada por la ecuación MDRD fue de 0.57 (p<0.001); al restringir el análisis a aquellos pacientes con valores de depuración menores a 60 ml/min, la correlación fue de 0.55 (p<0.001). La correlación entre la depuración de creatinina y la estimada por la ecuación de Cockcroft-Gault fue de 0.53 (p<0.001); al restringir el análisis a pacientes con valores de depuración menores a 60 ml/min, la correlación fue de 0.55 (p<0.001). La correlación entre las fórmulas de Cockcroft-Gault y MDRD fue de 0.84 (p<0.01). En pacientes con depuraciones por debajo de 60, fue de 0.87 (p<0.01). Los resultados no mostraron diferencias al restringir las observaciones a pacientes menores de 70 años.Conclusión:Aunque las ecuaciones de Cockcroft-Gault y MDRD guardan una buena correlación entre ellas, se correlacionan de manera subóptima con la depuración de creatinina realizada mediante la recolección de 24 horas, bajo condiciones clínicas habituales.

Abstract Introduction: The estimation of renal function is an important component of hospital care. To do this, estimates are usually used, based on serum creatinine levels. The most widely used equations are MDRD and Cockcroft-Gault. Objective: To evaluate the correlation of the Cockcroft-Gault and MDRD equations with the creatinine clearance value, based on 24-hour urine collection. Methods: In order to carry out this study, the records of the Clinical Pathology Service of Hospital Nacional HipólitoUnanue, a reference hospital in Lima (Peru), were used. Serum creatinine was measured using the Jaffe's method. Creatinine clearance was performed by simultaneous determinations of serum creatinine and urinary creatinine, obtained through 24-hour urine collection. Correlations were calculated using Pearson coefficient, considering significant values ​​of p<0.05. Results: 426 patients were included. The average age was 58.36 +/- 16.21 years, with a minimum age of 15 and a maximum of 91. There was a slight female predominance (51.2%). The correlation between creatinine clearance and that estimated by the MDRD equation was 0.57 (p<0.001); when restricting the analysis to those patients with clearance values ​​lower than 60 ml/min, the correlation was 0.55 (p <0.001). The correlation between creatinine clearance and that estimated by the Cockcroft-Gault equation was 0.53 (p<0.001); when the analysis was limited to patients with purification values ​​lower than 60 ml/min, the correlation was 0.55 (p <0.001). The correlation between Cockcroft-Gault and MDRD equations was 0.84 (p<0.01). In patients with purifications below 60, it was 0.87 (p<0.01). The results showed no differences when restricting observations to patients under 70. Conclusion: Although Cockcroft-Gault and MDRD equations keep a good correlation between them, this correlation is suboptimal with creatinine clearance performed through 24-hour collection, under usual clinical conditions.

Consecuencias de la selección inadecuada de la ecuación de estimación de la tasa de filtración glomerular / Consequences of inadequate selection of estimated glomerular filtration rate equation / Consequências da seleção inadequada da equação de estimação da taxa de filtração glomerular

El objetivo del trabajo consistió en evaluar, en una muestra de estudiantes, las consecuencias sobre la Tasa de Filtración Glomerular estimada (TFGe) por MDRD-4, MDRD-4 IDMS y CKD-EPI producidas por la selección inadecuada de las fórmulas según la trazabilidad de la creatininemia utilizada y valorar el efecto sobre la categorización por estadio G de TFG al utilizar valores numéricos de MDRD-4 y MDRD-4 IDMS≥60 mL/min/1,73 m². Se realizó un estudio descriptivo, analítico, de corte transversal con 100 alumnos de bioquímica, que participaron voluntariamente. Se determinó la creatininemia por métodos Jaffé cinéticos, valores trazables y no trazables al Isotopic Dilution Mass Spectroscopy (IDMS). La TFGe se calculó por las fórmulas MDRD-4, MDRD-4 IDMS y CKD-EPI introduciendo en cada fórmula valores de creatinina trazables y no trazables a IDMS. Los estudiantes se clasificaron por categoría G según los resultados. El mal empleo de las ecuaciones respecto a la trazabilidad de la creatininemia según fueron diseñadas cambió sensiblemente los valores de TFGe (p<0,05) y la proporción de jóvenes por estadio G respecto a lo hallado con el empleo adecuado (MDRD-4. G1: 67,4% vs. 53,7%; G2: 32,6% vs. 45,3%; G3a: 0,0% vs. 1,0%. MDRD-4 IDMS. G1: 37,9% vs. 59,0%; G2: 56,8% vs. 40,0%; G3a: 5,3% vs. 1,0%. CKD-EPI. G1: 70,5% vs. 85,3%; G2: 29,5% vs. 14,7%). El uso de valores numéricos para TFGe por MDRD-4 y MDRD-4 IDMS≥60 mL/min/1,73 m² infraestimó lo obtenido con CKD-EPI, que puede informarse numéricamente en ese rango. Ambas situaciones conllevan errores que afectan la categorización funcional renal de pacientes y la prevalencia en estudios epidemiológicos.

The objective of this work was to evaluate the consequences on the estimated Glomerular Filtration Rate (eGFR) by MDRD-4, MDRD-4 IDMS and CKD-EPI produced by the inadequate equation selection according to the creatinine traceability in a sample of biochemistry students and to assess the effect on G categorization if numerical values of the MDRD-4 and MDRD-4 IDMS equations≥60 mL/ min/1.73 m² were used. A descriptive, analytical, cross-sectional study was performed between 2014- 2016, 100 volunteer students of biochemistry were studied. Creatininemia was determined by kinetic Jaffé methods, traceable and non-traceable to Isotopic Dilution Mass Spectroscopy (IDMS). The eGFR was estimated by the MDRD-4, MDRD-4 IDMS and CKD-EPI formula, by feeding each formula with traceable and non traceable creatinine values to IDMS. Students were classified by category G according to the results obtained. Inappropriate equation use regarding the traceability of the creatinine for which they were designed significantly changed eGFR values (p<0.05) and the proportion of young people per G stage compared to what was found with adequate use (MDRD-4. G1: 67.4% vs. 53.7%; G2: 32.6% vs. 45.3%; G3a: 0.0% vs. 1.0%. MDRD-4 IDMS. G1: 37.9% vs. 59.0%; G2: 56.8% vs. 40.0%; G3a: 5.3% vs. 1.0%. CKD-EPI. G1: 70.5% vs. 85.3%; G2: 29.5% vs. 14.7%). The use of numerical values for eGFR by MDRD-4 and MDRD-4 IDMS≥60mL/min/1.73 m² underestimated what was obtained with CKD-EPI, which can be reported numerically in that range. Both situations involve errors that affect patient renal functional categorization and prevalence in epidemiological studies.

Este trabalho teve como objetivo avaliar as consequências sobre a Taxa de Filtração Glomerular estimada (TFGe) por MDRD-4, MDRD-4 IDMS e CKD-EPI produzidas pela seleção inadequada das fórmulas, segundo a rastreabilidade da creatininemia utilizada e o efeito sobre a categorização por estágio G de TFG ao utilizar valores numéricos de MDRD-4 e MDRD-4 IDMS≥60 mL/min/1,73 m². Este é um estudo descritivo, analítico e de corte transversal com 100 alunos de bioquímica, que participaram em forma voluntária. Foi determinada a creatininemia através do métodos Jaffé cinéticos, valores rastreáveis e não rastreáveis ao Isotopic Dilution Mass Spectroscopy (IDMS). A TFGe foi estimada pela fórmula MDRD-4, MDRD-4 IDMS e CKD-EPI introduzindo em cada fórmula valores de creatinina rastreáveis e não rastreáveis a IDMS. Os estudantes foram classificados por categoria G conforme os resultados. Uso indevido das equações a respeito da rastreabilidade da creatinina conforme foram desenhadas, mudou sensivelmente os valores de TFGe (p<0,05) e a proporção de jovens por estágio G em relação ao encontrado com o uso adequado adecuado (MDRD-4. G1: 67,4% vs. 53,7%; G2: 32,6% vs. 45,3%; G3a: 0,0% vs. 1,0%. MDRD-4 IDMS. G1: 37,9% vs. 59,0%; G2: 56,8% vs. 40,0%; G3a: 5,3% vs. 1,0%. CKD-EPI. G1: 70,5% vs. 85,3%; G2: 29,5% vs. 14,7%). Utilizar valores numéricos para TFGe por MDRD-4 e MDRD-4 IDMS≥60mL/min/1,73 m² infraestimou o obtido com CKD-EPI, que pode informar-se numericamente nesse intervalo. Ambas as situações conduzem a erros que afetam a categorização funcional renal de pacientes e a prevalência em estudos epidemiológicos.

Evolution of glomerulopathies associated with rheumatoid arthritis / Evolución de las glomerulopatías asociadas a la artritis reumatoidea

Abstract Introduction: Rheumatoid arthritis is one of the most common clinical syndromes within rheumatological conditions and its association with glomerular diseases is rare. Objective: To describe the histopathological findings in renal biopsies in patients with rheumatoid arthritis and to correlate them with the clinical and laboratory manifestations at the beginning, at 6 months and at one year of follow-up. Patients and Methods: This is a retrospective observational study conducted in the Hospital de Clinicas "Jose De San Martin" in Buenos Aires, Argentina; Where we included 41 patients diagnosed with RA (ACR 1987) in a period of 20 years. Histopathological diagnoses of membranous nephropathy (MN), minimal change disease (MCD), secondary amyloidosis (AA), focal and segmental glomerulosclerosis (FSGS); mesangial glomerulopathy (MGP) and glomerulonephritis with extracapillary proliferation (GNEC) were included. Histopathological description, different treatments, years of evolution of rheumatoid arthritis Clinical and laboratory characteristics were analyzed during the first 6 months and one year of follow-up in order to determine the progression of renal failure calculated through the formula of MDRD of 4 variables (Modification of diet in renal disease) and the increase of proteinuria. Results: The most frequent histological finding was amyloidosis with 34,1 % (n=14), followed by mesangial glomerulopathy 21,9 % (n=9), membranous nephropathy 19,5 % (n=8), glomerulonephritis with extracapillary proliferation 12,1 % (n=5), focal and segmental glomerulosclerosis 7,3 % (n=3) and minimal change disease 8,2 % (n=2). Nephrotic syndrome was the most frequent presentation in patients with amyloidosis in 85,7 %, microhematuria occurred in 100 % of patients with MPG and in 80 % of patients with GNEC. In patients with AA, moderate to severe interstitial fibrosis occurred in 85,7 %, followed by GNEC and NM with 80 % and 40 % respectively. The 24-hour proteinuria, creatinine and glomerular filtration rate estimated by MDRD at 6 months and 12 months were evaluated. Concluding, that patients with AA, FSGS and GNEC had greater progression of renal failure at 12 months; the opposite occurred in patients with minimal change disease (MCD) and mesangial glomerulopathy (MGP) who had a lower progression of renal failure at one year of follow-up; There was a correlation in the glomerulopathies that had greater deterioration of the renal function had greater interstitial tubule involvement as was the case of amyloidosis. The glomerulopathies that presented greater proteinuria at the beginning were membranous nephropathy, amyloidosis and minimal change disease. Both membranous nephropathy and minimal change disease had partial remission at one year, in contrast to amyloidosis, which showed progression of proteinuria at 12 months of follow-up. Conclusion: The glomerulopathies that presented greater progression of renal failure at 1 year based on the estimation by MDRD 4, had a higher renal tubular interstitial involvement in renal biopsy and these were amyloidosis (AA), segmental focal glomerulosclerosis (FSGS), glomerulonephritis with proliferation extracapillary On the other hand, those with the best evolution in relation to the degree of proteinuria and the glomerular filtration rate determined by the MDRD4 equation were mesangial glomerulopathy, minimal change disease, and membranous nephropathy.

Resumen Introducción: La artritis reumatoidea (AR) es uno de los síndromes clínicos con mayor frecuencia dentro de las afecciones reumatológicas y su asociación con las enfermedades glomerulares es poco frecuente. Objetivo: Describir los hallazgos histopatológicos en las biopsias renales en pacientes con artritis reumatoidea y correlacionarlos con las manifestaciones clínicas y de laboratorio al inicio, a los 6 meses y al año de seguimiento. Pacientes y métodos: Es un estudio observacional retrospectivo realizado en un hospital Universitario en Buenos Aires, Argentina. Se incluyeron 41 pacientes con diagnóstico de artritis reumatoidea de acuerdo a los criterios establecidos por el Colegio Americano de Reumatología publicados en 1987; en un período de 20 años. Se incluyeron diagnósticos histopatológicos de nefropatía membranosa (NM), enfermedad de cambios mínimos (ECM), amiloidosis secundaria (AA), gloméruloesclerosis focal y segmentaria (GEFS); glomerulopatía mesangial (GPM) y glomerulonefritis con proliferación extracapilar (GNEC). Las características clínicas, de laboratorios, la descripción histopatológica, los años de evolución de la artritis reumatoidea y los diferentes tratamientos fueron analizados durante los primeros 6 meses y al año del seguimiento. Con esto, se buscó determinar la progresión de la insuficiencia renal, calculada a través de la fórmula de MDRD (Modification of Diet in Renal Disease) de 4 variables y el aumento de la proteinuria. Resultados: El hallazgo histológico más frecuente fue la amiloidosis, con un 34.1 % (n=14), seguido de la glomerulopatía mesangial (21,9 %, n=9), la nefropatía membranosa (19,5 %, n=8), la glomerulonefritis con proliferación extracapilar (12,1 %, n=5), la glomeruloesclerosis focal y segmentaria (7,3 %, n=3) y enfermedad de cambios mínimos (8,2 %, n=2). El síndrome nefrótico fue la forma de presentación más frecuente en los pacientes con amiloidosis (en un 85,7 % de los casos), la microhematuria se presentó en el 100 % de los pacientes con GPM y en el 80 % de los pacientes con GNEC. En el 85,7 % de los pacientes con AA, se presentó fibrosis intersticial moderada a severa, mientras que en la GNEC y la NM la fibrosis se observó en un 80 % y 40 % respectivamente. Se evaluó la proteinuria de 24 horas, la creatinina y la filtración glomerular estimada por MDRD a los 6 y a los 12 meses. Se concluyó que los pacientes con AA, GEFS y GNEC presentaron mayor progresión de la insuficiencia renal a los 12 meses. Lo contrario sucedió en los pacientes con enfermedad de cambios mínimos (ECM) y glomerulopatía mesangial (GPM), los cuales tenían una menor progresión de la insuficiencia renal al año de seguimiento. Hubo una correlación entre las glomerulopatías que tenían mayor deterioro de la función renal en las cuales se observó a su vez, mayor compromiso tubulointersti-cial, (este fue el caso de la amiloidosis). Las glomerulopatías que presentaban mayor proteinuria al inicio eran la nefropatía membranosa, la amiloidosis y la enfermedad de cambios mínimos. Tanto la nefropatía membranosa como la enfermedad de cambios mínimos, tenía remisión parcial tras un año, a diferencia de la amiloidosis, la cual presentaba progresión de la proteinuria a los 12 meses de seguimiento. Conclusión: Las glomerulopatías que presentaron mayor progresión de la insuficiencia renal al año, con base en la estimación por MDRD4, tenían en la biopsia renal mayor compromiso tubulointersticial. Estas fueron la amiloidosis secundaria, la glomeruloesclerosis focal y segmentaria, y glomerulonefritis con proliferación extracapilar. Por el contrario, las de mejor evolución respecto al grado de proteinuria y tasa de filtrado glomerular determinado por MDRD4, fueron la glomerulopatía mesangial, la enfermedad de cambios mínimos y la nefropatía membranosa.

Comparação das equações MDRD e CKD-EPI na estimativa da taxa de filtração glomerular em pacientes diabéticos e hipertensos não diagnosticados com doença renal crônica atendidos em ambulatório de um hospital universitário / Comparing the equation MDRD & CKD-EPI in the estimate of glomerular filtration rate in diabetic and hypertensive patients not diagnosed with chronic kidney disease served in a outpatient university hospital

A demonstração clínica da função renal é primordial para a prática médica. A taxa de filtração glomerular (TFG) é uma medição direta da função renal e é reduzida antes do início dos sintomas deinsuficiência renal. Determinar essa taxa é crucial para o diagnóstico e estadiamento da doença renal crônica (DRC) e para a avaliação da resposta aotratamento. A TFG pode ser estimada utilizando-se equações matemáticas empíricas baseadas na dosagem de creatinina sérica, como a MDRD e CKD-EPI. Seu uso tem sido incentivado como um meio simples, rápido e viável da avaliação da função renal. O objetivo deste estudo foi comparar a eTFG gerada pelas equações MDRD e CKD-EPI em indivíduos não diagnosticados com DRC. Foram selecionados noventa pacientes atendidos no Ambulatório do Hospital Universitário do Oeste do Paraná (HUOP). Entre os pacientesselecionados para o estudo, a e TFG média obtida, utilizando-se as fórmulas CKD-EPI e MDRD, foi de 91ml/min/1,73 m2 (DP±28) e 93 ml/min/1,73 m2 (DP±41). A taxa global de pacientes com eTFG <60 ml/min/1,73 m2 , utilizando-se o cálculo do CKD-EPI, foi de 14%e, com o MDRD, foi de 17%. Foi possível concluir que a TFG de pacientes ambulatoriais apresentando ou não comorbidades pré-existentes pode ser estimada tanto pela equação CKD-EPI quanto pelo estudo MDRD...

Eficacia de las fórmulas MDRD-abreviada y Cockcroft-Gault para la detección de insuficiencia renal crónica en la atención primaria / Effectiveness of the Cockcroft-Gault and MDRD-abbreviated formula for the detection of chronic renal failure in primary care

Se realizó un estudio comparativo y prospectivo de tipo cohortes, que incluyó a 1038 pacientes, atendidos en el consultorio médico No. 5 de la Policlínica Universitaria "Joel Benítez Borges" de Cauto Cristo, provincia de Granma, desde abril del 2011 hasta noviembre del 2012, a fin de determinar la eficacia de las fórmulas MDRD-abreviada, Cockcroft-Gault y Cockcroft-Gault corregida para la detección de insuficiencia renal crónica en los afectados con creatinina sérica normal. Se comparó el grupo de pacientes con creatinina sérica normal según filtrado glomerular normal o disminuido. La prevalencia de insuficiencia renal crónica fue de 11,9, 10,9 y 11,0 % para las fórmulas MDRD-abreviada, Cockcroft-Gault y Cockcroft-Gault corregida, respectivamente. Se demostró la sencillez y eficacia de la fórmula MDRD-abreviada en el cribaje de la insuficiencia renal crónica, fundamentalmente en mujeres añosas e hipertensas.

A comparative and prospective study of cohorts type, which included 1038 patients, assisted in the doctor's office No. 5 of "Joël Benítez Borges" University Polyclinic in Cauto Cristo, Granma province was carried out from April, 2011 to November, 2012, in order to determine the effectiveness of the MDRD-abbreviated formula, and the Cockcroft-Gault and Cockcroft-Gault formulas corrected for the detection of chronic renal failure in the affected patients with normal serum creatinine. The group of patients with normal serum creatinine was compared according to normal or decreased glomerular filtrate. The prevalence of chronic renal failure was of 11,9, 10,9 and 11,0 % for the MDRD-abbreviated formula, Cockcroft-Gault and Cockcroft-Gault corrected, respectively. It was demonstrated the simplicity and effectiveness of the MDRD-abbreviated formula in the screening of the chronic renal failure, mainly in aged and hypertensive women.

Estimación de la tasa de filtración glomerular usando las ecuaciones CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) y MDRD 4 (Modification of Diet in Renal Disease) en pacientes diabéticos tipo 2 atendidos en HNERM / Estimation of glomerular filtration rate using the equations CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) and MDRD (Modification of Diet in Renal Disease) in type 2 diabetic patients treated at HNERM

Introducción: El filtrado Glomerular es el marcador de función renal más aceptado. Para su estimación se han desarrollado diversos métodos: depuración de creatinina en orina de 24 horas (DCC) o ecuaciones derivadas de la creatinina sérica. Dichas ecuaciones permiten el diagnóstico y estratificación de la Enfermedad Renal Crónica. Las ecuaciones más usadas son MDRD y CKD EPI que incorpora datos sobre edad, sexo, etnia y creatinina sérica. La asociación americana de diabetes en 2010 recomienda el uso de la ecuación MDRD para la estratificación de la ERC en el paciente diabético; Sin embargo en estadios iniciales de daño renal dicha ecuación tiende a subestimar el valor real. A la fecha la ecuación CKD-EPI está demostrando mejor correlación en estadios tempranos de daño sin embargo los estudios no son concluyentes sobre su utilidad. Objetivo: Determinar la correlación y el grado de concordancia entre la ecuación de CKD-EPI y MDRD con la depuración de creatinina en orina de 24 horas para la estimación de la tasa de filtrado glomerular en pacientes diabéticos tipo 2, mayores de edad que acuden al servicio de Patología Clínica sección Bioquímica-depuración de creatinina del HNERM, en el periodo octubre-diciembre 2013. Metodología: Es un estudio Analítico comparativo, prospectivo observacional. Se obtuvo una muestra de 152 pacientes diabéticos, se aplicó el test de correlación de Spearman, se aplicó el coeficiente de correlación de concordancia, y para determinar el bias respecto a la DCC se utilizó la gráfica de Bland Altman. Resultados: Se evaluó las ecuaciones CKD EPI, MDRD 4 con la DCC respectivamente la ecuación CKD EPI tuvo mejor correlación R 0.86, se evaluó el grado de concordancia con el índice Kappa k 0.69 (muy bueno) IC 0.61-0.78, y la ecuación MDRD 4, 0.63, IC 0.56 y 0.71. Se evalúo el bias entre los métodos y se observa en toda la población que la ecuación CKD EPI y MDRD 4 sobrestiman la TFG en relación a la DCC, en -3.1 y -8.1 respectivamente...

Introduction: Glomerular filtration is the most widely accepted marker of renal function. Nowadays, there have been developed various methods: Urine creatinine clearance 24 hours (OCC) or equations derived from serum creatinine. These equations allow the diagnosis and stratification of chronic kidney disease. The MDRD and CKD EPI equations are the most used, which ones incorporate data on age, sex, ethnicity and serum creatinine. At 2010 The American Diabetes Association recommended the use of the MDRD equation for stratification of CKD in diabetic patients; However in early stages of kidney damage this equation tends to underestimate the true value. To date, the CKD-EPI equation is proving better correlation in early stages of damage but studies are inconclusive about its usefulness. Objective: To determine the correlation and the concordance between the CKD-EPI and MDRD with creatinine clearance in 24 hour urine for estimating glomerular filtration rate in type 2 diabetic patients, who came to Clinical Pathology service biochemically creatinine clearance section of HNERM, in the period from October to December 2013. Methods: there was an analytical-comparative, prospective observational study. A sample of 152 diabetic patients was obtained, the Spearman correlation test was applied, the concordance correlation coefficient is applied, and to determine the bias respect to the DCC was used the graph of Bland Altman. Results: it was analyzed CKD EPI and MDRD 4 equations with the DCC respectively the CKD EPI had better correlation R 0.86, the degree of agreement was analyzed with the Kappa index k 0.69 (very good) CI 0.61 to 0.78, and the MOR04 0.63, CI 0.56 to 0.71. The bias between the methods was evaluated; CKD EPI and MDRD 4 overestimate GFR in relation to the DCC, -3.1 and -8.1 respectively, the CKD EPI has lower bias. Conclusions: The CKD EPI is comparable with DCC in 24-hour urine and has better performance and correlation than MDRD equation 4.

Low rates of automatic reporting of estimated glomerular filtration rate in Southern Brazilian laboratories.

OBJECTIVES: The aim of this study was to evaluate the rate of eGFR reporting in Southern Brazilian laboratories. DESIGN AND METHODS: The eGFR automatic reporting, as assessed by Modification of Diet in Renal Disease (MDRD) and/or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) creatinine-based equations, was evaluated in a representative cross-sectional sample. A standardized questionnaire to obtain this information was given out by mail or email. RESULTS: Five-hundred fifty laboratories, evenly distributed in the different state regions, completed the questionnaire. The eGFR was automatically reported by 54 (9.8%) laboratories, and the MDRD was the most commonly used equation (94.5%). The Jaffe methods were the most employed technique (94%) to measure serum creatinine. CONCLUSION: The automatic eGFR reporting rate was unacceptably low, emphasizing the crucial role of educating medical teams and laboratories on the importance of having these tools available to optimize detection of renal disease and proper treatment.

Comparison between IDMS-traceable Jaffe and enzymatic creatinine assays for estimation of glomerular filtration rate by the CKD-EPI equation in healthy and diabetic subjects.

OBJECTIVES: The aim of this paper was to compare the agreement between creatinine measured by Jaffe and enzymatic methods and their putative influence on eGFR as calculated by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation in healthy and diabetic individuals. DESIGN AND METHODS: Cross-sectional study conducted in 123 adult southern Brazilians with GFR>60 mL/min/1.73 m² (53 patients with type 2 diabetes, 70 healthy volunteers). Mean age was 49±16 years (range of 19-86). Most were female (55%) and white (83%). Creatinine was measured by a traceable Jaffe method (Modular P, Roche Diagnostic) and by an enzymatic method (CREA plus, Roche/Hitachi 917). GFR was measured by the 5¹Cr-EDTA single-injection method. RESULTS: Serum creatinine measured by the Jaffe and enzymatic methods was similar in healthy subjects (0.79±0.16 vs. 0.79±0.15 mg/dL, respectively, P=0.76), and diabetic patients (0.96±0.22 vs. 0.92±0.29 mg/dL, respectively, P=0.17). However, the correlation between the two methods was higher in the healthy group (r=0.90 vs. 0.76, P<0.001). The difference between Jaffe creatinine and enzymatic creatinine was <10% in 63% of cases in the healthy group and 40% of cases in the diabetes group (P=0.018). In the subset of patients with diabetes, eGFR based on enzymatic assay results showed better agreement with measured GFR than did eGFR based on Jaffe results. CONCLUSION: Jaffe and enzymatic creatinine methods show adequate agreement in healthy subjects, but in the presence of diabetes, the enzymatic method performed slightly better.

Prevalencia de insuficiencia renal crónica mediante las fórmulas de Cockcroft-Gault y Modificación de Dieta en la Enfermedad Renal: Matanzas, 2010 / Prevalence of the chronic renal insufficiency by means of the Cockcroft-Gault and Diet modification in the renal disease formulas: Matanzas, 2010

Fundamento: la insuficiencia renal crónica es la pérdida gradual, progresiva e irreversible de las funciones renales. Las fórmulas más empleadas para su diagnóstico son las de Cockcroft-Gault y la Modificación de Dieta en la Enfermedad Renal. En Matanzas se habían utilizado en estudios poblacionales.Objetivos: calcular la prevalencia de la insuficiencia renal crónica en el municipio de Matanzas y comparar ambas fórmulas. Métodos: se realizó un estudio descriptivo de tipo transversal. Muestra 2 326 personas. Las variables utilizadas fueron edad, sexo, peso, talla, color de la piel y creatinina sérica. Se utilizaron los intervalos de confianza del 95 por ciento para comparar las prevalencias por ambos métodos. Resultados: la prevalencia fue de 6,4 por 100 personas por Cockcroft-Gault y 5,0 por Modificación de Dieta en la Enfermedad Renal. Se incrementó directamente proporcional a la edad, el sexo femenino fue el más afectado, al igual que el color de piel blanca. No hubo diferencias significativas entre los datos de ambos métodos en el análisis de estas variables. La media de filtrado glomerular fue superior por la fórmula de Cockcroft-Gault. Igualmente por esta ecuación, fue superior la prevalencia en el grupo de 65 a 74 y en las personas con peso saludable. Conclusiones: se considera que ambos métodos son válidos para el cálculo de FG y por tanto para el diagnóstico de insuficiencia renal crónica, por su sencillez, y bajo costo, cuando se trabaja con grupos poblacionales grandes.

Fundament: the chronic renal insufficiency is the gradual, progressive and irreversible lost of the renal functions. The Cockcroft-Gault and the Diet Modification in the renal disease formulas are the most used ones for its diagnosis. In Matanzas they had been used in population studies. Objectives: calculating the prevalence of the chronic renal insufficiency in the municipality of Matanzas and comparing both formulas. Methods: we carried out a cross-sectional descriptive research. The sample was composed by 2 326 persons. The used variables were age, genre, weight, size, skin color, and serum creatinine. We used the confidence intervals of 95 percent to compare the prevalence of both methods. Results: the prevalence was 6,4 per 100 people for the Cockcroft-Gault, and 5,0 for the Diet Modification in the Renal Disease. There it was a direct increase in relation with age; the female genre was the most affected, and also the white skin color. There were not significant differences between the data of both methods in the analysis of these variables. The average of the glomerular filtrate was higher by means of the Cockcroft-Gault. Also the prevalence in the 65-74 age group and in the persons with healthy weight was higher for this equation.Conclusions: we consider that both methods are valid for calculating the glomerular filtrate and therefore for the diagnosis of the chronic renal insufficiency, because of its easiness and low cost, when working with big population groups.

Tasa de filtración glomerular mediante depuración de creatinina y fórmula MDRD en la enfermedad renal crónica / Glomerular Filtration Rate estimate by creatinine clearence and MDRD formula in chronic renal disease

El método más usado para medir la Tasa de Filtración Glomerular (TFG) es la Depuración de Creatinina a través de la recolección de orina de 24 horas. La precisión de la depuración depende de una orina recogida adecuadamente y ésta representa la principal limitación, ya que recoger orina de 24 horas resulta difícil para la mayoría de las personas. Debido a estas limitaciones se han desarrollado fórmulas predictivas. Entre éstas se encuentra la fórmula MDRD (Modification of Diet in Renal Disease), la cual es la más recomendada por las sociedades científicas debido a su facilidad de implementación y sensibilidad para detectar la Enfermedad Renal Crónica (ERC). El objetivo de esta investigación fue comparar la TFG determinada por la Depuración de Creatinina en orina de 24 horas y aplicando la fórmula MDRD en pacientes con diferentes grados de ERC. La muestra fue de 93 pacientes mayores de 18 años de ambos sexos con diferentes estadios de ERC, a quienes se les determinó depuración de creatinina en orina de 24 horas y además se estimó la TFG mediante la fórmula MDRD. Los resultados muestran que la fórmula MDRD subestima la TFG determinada por la depuración de creatinina, observándose una diferencia estadísticamente significativa (p=0.000) cuando se compararon ambos métodos en la totalidad de la muestra. Al hacer la comparación por estadios de ERC se observó una significativa subestimación en los estadios 1, 2 y 3 (p=0.000), (p=0.010) y (p=0.003), respectivamente. En conclusión, la fórmula MDRD subestima la TFG determinada por la depuración de creatinina, sobre todo en los primeros estadios de la ERC.

The most widely used method for determining the Glomerular Filtration Rate (GFR) is a 24hour urine Creatinine Clearance test. The precision of this test depends on whether urine has been properly collected, which is a major limitation, as the 24-hour urine collection process seems difficult to most patients. Due to such limitation, some predicting formulae have been developed. Among these formulae, the MDRD (Modification of Diet in Renal Disease) formula is highly recommended by scientific societies, as it is easily implemented and highly sensitive in detecting Chronic Renal Disease (CRD). The purpose of this study was to compare GFR determination by the 24-hour urine creatinine-clearance test, and the application of the MDRD formula in patients with various levels of CRD. The sample consisted of 93 subjects over 18 years of age, of both genders, and at various stages of CRD. They had a 24-hour urine creatinine clearance test done, and the GFR was estimated by applying the MDRD formula. Results demonstrate that the MDRD formula underestimates the GFR obtained through creatinine clearance, with a statistically significant difference (p=0.000) when both methods were compared in the whole sample. When CRD stages were compared, a significant underestimation of stages 1, 2 and 3 was observed (p=0.000), (p=0.010) and (p=0.003), respectively. In conclusion, the MDRD formula underestimates the GFR determined by creatinine clearance, mainly during the first stages of CRD.

Enfermedad renal crónica determinada mediante la creatinina sérica / Chronic kidney disease as measured by serum creatinine

La enfermedad renal crónica se relaciona con un mayor riesgo de enfermedad renal crónica terminal, de enfermedades cardiovasculares y de muerte, por lo que se requiere sudiagnóstico desde las primeras etapas de la enfermedad. Para ello, se disponen de un gran número de ecuaciones para estimar la tasa de filtración glomerular basadas en la concentración de creatinina sérica. Si bien la creatinina no es el analito ideal para estimar la filtración glomerular, ésta continuará empleándose hasta que haya una amplia disponibilidad en el medio de otros marcadores, como la cistatina C, por lo que el laboratorio clínico debe velar por la calidad analíticade los resultados y por lo tanto, debe determinar la creatinina a través de un método estandarizado frente a los procedimientos de medida de referencia. El objetivo de este módulo es revisar ladetección de la enfermedad renal crónica desde sus etapas iniciales, a partir de la creatinina sérica y de la estimación de la tasa de filtración glomerular.

Chronic kidney disease is associated with an increased risk of end-stage renal disease,cardiovascular diseases and death; hence, it is necessary to make a diagnosis in the early phasesof the disease. Many equations for estimating glomerular filtration rates are available for thispurpose, and are based on serum creatinine concentration. Although creatinine is not the idealanalyte to gauge glomerular filtration rate, it will be used until there is extensive availability of othermarkers, such as cystatin C. On these grounds, clinical laboratories must offer results with highstandards of quality control, and accordingly, they must measure serum creatinine with suitablemethods, previously standardized by reference measurement procedures. The aim of this moduleis to assess early diagnosis of chronic kidney disease through serum creatinine quantification andglomerular filtration rate estimation.

Correlación entre el aclaramiento de creatinina y la fórmula MDRD-4 en la estimación del filtrado glomerular / Correlation between creatinine clearance and MDRD-4 formula in the estimation of the glomerular filtrate

La creatinina sérica y el aclaramiento de creatinina (ClCr) son los métodos mayoritariamente empleados como medida del Filtrado Glomerular (FG), procedimientos no exentos de problemas tanto preanalíticos como analíticos. En los últimos años se viene proponiendo la utilización de fórmulas predictivas del FG. Buscamos comprobar la correlación entre el método analítico y el estimado por la ecuación de MDRD-4. Se estudiaron retrospectivamente 89 pacientes, con un promedio de 51 ± 14 años; 31 varones y 58 mujeres. Aunque la media del FG estimada por la fórmula MDRD-4 fue de 66 ± 28.83 ml/min y la obtenida con la depuración de creatinina fue de 62±30.22ml/min. (p<0.05); se encontró una correlación positiva entre ambos métodos (r=0,796; p=0,001). En nuestra población la ecuación MDRD-4 presenta una buena equivalencia con el ClCr y podría utilizarse para evaluar la función renal en pacientes con riesgo de desarrollar enfermedad renal crónica (ERC).

Serum creatinine and creatinine clearance (CrCl) methods are mostly used as measures of glomerular filtration (GF) and are procedures that are not exempt from both pre-analytical and analytical problems. In recent years, it has been proposed the use of predictive formulas of GF. In this study, we sought to verify the correlation between the analytical method and the estimated by the MDRD-4 formula. Eighty nine patients were studied retrospectively, they had a mean age of 51±14 years and there were 31 males and 58 females. Though the mean GF estimated by the MRDR-4 formula was 66 ± 28.83 ml/min and the obtained by creatinine depuration was 62 ± 30.22ml/min. (p<0.05), a positive correlation between both methods was found (r=0.796; p=0.001). In our population, the MRDR-4 formula has a good equivalence with the CrCl and could be used to assess the renal function of patients at risk of developing chronic kidney disease (CKD).

Incidencia de enfermedad renal crónica y factores de riesgo para su desarrollo en pacientes postrasplante hepático en el Hospital Universitario Fundación Santa Fe de Bogotá 2004-2008 / Incidence of chronic kidney disease and risk factors for patients who underwent liver transplantation at Fundación Santa Fe University Hospital from 2004 to 2008

Antecedentes: La enfermedad renal crónica (ERC) se desarrolla frecuentemente después de someter a pacientes a trasplante de órganos sólidos como hepático, cardíaco, pulmonar, intestino delgado, y se asocia con un aumento en la morbimortalidad, costos y deterioro de la calidad de vida del paciente. El desarrollo de enfermedad renal crónica es una complicación común en pacientes postrasplante hepático. Es definida como una tasa de filtración glomerular entre 60 y 29 ml/min/1,73 m² de área de superficie corporal en el postoperatorio. Múltiples factores contribuyen al riesgo de desarrollar ERC en este grupo de pacientes. Entre los más importantes se encuentran la función renal previa al trasplante, medida por la fórmula MDRD (Modification of Diet in Renal Disease), injuria renal aguda durante el perioperatorio, inmunosupresores como los inhibidores de calcineurina. Durante los primeros seis meses del trasplante es cuando ocurre el deterioro mas rápido de la función renal y en meses posteriores esta declina lentamente. Es importante determinar nuestra incidencia de falla renal crónica, el grado de severidad de esta según la clasificación y los factores de riesgo en pacientes de trasplante hepático. El objetivo de este estudio es determinar la incidencia de enfermedad renal crónica y los factores de riesgo para su desarrollo en pacientes postrasplante hepático en el Hospital Universitario Fundación Santa Fe de Bogotá en el periodo comprendido entre enero del 2004 y noviembre de 2008. Materiales y métodos: Es un estudio descriptivo, retrospectivo. La población, fueron los pacientes llevados a trasplante hepático en el Hospital Universitario Fundación Santa Fe de Bogotá entre enero 1 del 2004 y noviembre 11 del 2008, que tuvieran previo al trasplante una función renal normal, calculada por MDRD, excluyendo insuficiencia renal previa al trasplante y aquellos que requirieron trasplante combinado hígado-riñón. Resultados: De 79 pacientes incluidos en el estudio, 27 (34,2% IC 95% 23,9-45,7) presentaron falla renal al sexto mes de seguimiento con un MDRD de estadio 2. De los 27 pacientes que desarrollaron falla renal crónica postrasplante a los seis meses de seguimiento, 6 (22,2%) tenían diagnóstico de cirrosis por NASH; 5 (18,5%) tenían diagnóstico de hepatitis C. Los 27 pacientes que desarrollaron falla renal crónica al sexto mes de seguimiento, tenían un MDRD pretrasplante en promedio de 89,4 ml/min/m²/SC. La falla renal crónica postrasplante es una complicación que viene en ascenso y que se asocia a factores de riesgo pretrasplante y postrasplante, como son hipertensión arterial, diabetes mellitus, hepatitis C e inmunosupresión. Conclusiones: Podemos decir que existe una tendencia a que los pacientes con diagnóstico pretrasplante de cirrosis por NASH y hepatitis C desarrollen más falla renal crónica. La inmunosupresión en el postrasplante inmediato influye en el desarrollo de falla renal crónica; en nuestro trabajo se observa como ciclosporina A, en un gran porcentaje presente en los pacientes que desarrollaron falla renal crónica. Se necesitarán nuevos estudios para determinar asociación entre estos factores de riesgo y el desarrollo de falla renal crónica.

Background: Chronic Renal Failure (CRF) frequently develops in patients who undergo transplantation of solid organs such as livers, hearts, lungs, and small intestines. CRF increases morbidity and mortality rates, increases costs and results in deterioration in the quality of patients' lives. The development of CRF is a common complication in post-liver transplant patients. It is defined as a glomerular filtration rate between 29 and 60 ml/min/1.73 m² of body surface area during post-surgical procedures. Multiple factors contribute to the risk of developing CRF in this group of patients. The most important among these factors are renal function prior to transplantation as measured by MDRD formula (Modification of Diet in Renal Disease), acute perioperative renal failure, and immune-suppressors such as calcineurin inhibitors. During the first six months after transplantation renal function deteriorates rapidly, but declines slowly thereafter. It is important to determine our incidence of chronic renal failure, the degree of severity according to the classification and the risk factors in patients who underwent liver transplantation. The aim of this study is to determine the incidence of chronic renal disease and the risk factors affecting post-liver transplant patients in the Fundación Santa Fe de Bogota University Hospital from January 2004 to November 2008. Materials and methods: This was a descriptive and retrospective study of a population of patients who had undergone liver transplantation in the Fundación Santa Fe de Bogota University Hospital between January 1, 2004 and November 11, 2008. These patients presented normal renal functions as measured by the MDRD formula. We excluded patients with previous renal insufficiency and combined liver-kidney transplantation patients. Results: 79 patients were included in the study. 27 (34.2% CI 95% 23.9 - 45.7) had developed Stage 2 MDRD renal failure by the 6th month of surveillance. 6 of the 27 patients (22.2%) presented cirrhosis resulting from NASH. 5 of the 27 (18.5%) presented hepatitis C. The 27 patients who developed chronic renal failure by the 6th month of surveillance presented an average MDRD score of 89.4 ml/min/m²/SC prior to transplantation. Chronic renal failure following transplantation is an increasingly common complication, associated with risk factors prior to and following transplantation. These factors include arterial hypertension, diabetes mellitus, hepatitis C and immunosuppression. Conclusions: Patients with pre-transplantation diagnoses of cirrhosis resulting from NASH or of hepatitis have a tendency to develop chronic renal failure. Immunosuppression immediately after transplantation influences the development of chronic renal failure. In our study we observed high percentages of cyclosporine A in patients who developed chronic renal failure. New studies are needed to determine the association between these risk factors and the development of chronic renal failure.

Comparación entre las ecuaciones CKD-EPI y MDRD para la estimación del filtrado glomerular en pacientes con enfermedad renal crónica / Comparison between CKD-EPI and MDRD-equations to estimate glomerular filtration rate in chronic kidney disease patients

La ecuación MDRD para la estimación del índice de filtrado glomerular (IFG), es la estrategia más utilizada para evaluar pacientes con enfermedad renal crónica (ERC). Sin embargo, puede subestimar el IFG con el riesgo de asignar al paciente a estadios más avanzados de ERC. La nueva ecuación CKD-EPI, mejoraría la exactitud y precisión de las estimaciones. Sus autores sugieren que reemplace a la anterior. No habiendo comparaciones de estas ecuaciones aplicadas en un gran número de pacientes en nuestro país, nuestro objetivo fue realizarla en una amplia cohorte de pacientes. Se evaluó la concordancia de asignación en estadios de ERC entre ambas ecuaciones, tomando como referencia los datos surgidos de MDRD. Se calculó la media de las diferencias de los IFG obtenidos empleando ambas ecuaciones y se aplicó el análisis estadístico de Bland-Altman. Se estudió una cohorte de 9 319 pacientes con una media de creatinina sérica de 1.60 ± 1.03 mg/dl, 67% de sexo femenino y edad media 58 ± 20 años. En el grupo total, CKD-EPI presentó una media de IFG 0.61 ml/min/1.73 m² mayor que MDRD (p: NS). En los estadios 2 y 3A las medias del IFG fueron respectivamente 6.95 ± 4.76 y 3.21 ± 3.31, y la concordancia de 81 y 74%. El porcentaje de pacientes con un IFG menor de 60 ml/min/1.73 m², se redujo de 76.3% (MDRD) a 70.1% (CKD-EPI). Por lo tanto, la nueva ecuación CKD-EPI disminuye el número de pacientes con IFG debajo de 60 ml/min/1.73 m² y asigna estadios de IFG más elevado a un número mayor de pacientes.

The MDRD equation to estimate glomerular filtration rate (GFR) is the most widely used strategy to assess chronic kidney disease. Nonetheless, for the individual patient the true GFR can be underestimated with the risk of diagnosing a more elevated CKD stage. This novel CKD-EPI equation would improve accuracy and precision of estimations, and several authors recommend this new equation replace the former. In our country there is only a limited registration of these comparisons performed on a large number of patients. Therefore, our aim was to develop a comparison in a wide cohort of patients. The concordance between both equations to assign the GFR stages was determined by using the MDRD formula as a reference. The mean difference of GFR obtained with both equations as well as the Bland-Altman analysis were calculated. A cohort of 9 319 individuals, of whom 67% were females, aged 58 ± 20 years, with serum creatinine values of 1.6 ± 1.03 mg/dl, was studied. In the whole group, CKD-EPI displayed an average GFR 0.61 ml/min/1.73 m² larger than MDRD (p: NS). For CKD stages 2 and 3A the mean estimated GFR difference was 6.95 ± 4.76 and 3.21 ± 3.31, while the concordance was 81 and 74% respectively. The percentage of patients with GFR < 60 ml/min/1.73 m², decreased from 76.3% with the former equation to 70.1% with the latter. The novel equation CKD-EPI reduces the number of patients with GFR values lower than 60 ml/min/1.73 m² and consequently assigns a higher GFR stage to a considerable quantity of individuals.

Detección precoz de Enfermedad Renal Crónica / Early detection of Chronic Kidney Disease. Multidisciplinary document / Detecção precoce de doença renal Crônica

El aumento de la prevalencia de pacientes con Enfermedad Renal Crónica (ERC), la ha convertido en un problema de Salud Pública mundial, no sólo por el requerimiento de tratamiento sustitutivo renal, sino porque el desarrollo de enfermedad cardiovascular constituye la primera causa de muerte en estos pacientes. La creatinina plasmática (Crp) no siempre resulta un marcador precoz, pues su valor en sangre se eleva por encima del límite superior del intervalo de referencia cuando el Índice de Filtrado Glomerular (IFG) disminuye a la mitad. La medición del IFG con marcadores exógenos es el mejor indicador para evaluar la función renal (FR), aunque su uso en la práctica clínica se reserva para situaciones especiales. El Índice de depuración de creatinina (IDC) puede presentar errores por causa de una mala recolección de orina. Además, sobreestima el IFG debido a que la creatinina, además de ser excretada, se secreta a nivel tubular. La utilización de fórmulas asociadas a Crp está recomendada por la mayoría de las sociedades científicas. La ecuación MDRD-4 se adoptó por consenso "IFGe (mL/min/1,73 m²)= 186 x (Crp) -1.154 x (edad) -0.203 x (0,742 mujer) x (1,212 raza negra)". El factor inicial es 175 cuando el resultado de Crp es trazable a Espectrometría de Masa con Dilución Isotópica (EM-DI). Esta fórmula no es aplicable en casos de embarazadas, hospitalizados, menores de 18 o mayores de 70 años, amputados, etc. Dado que la medición de Crp es la mayor fuente de error para el cálculo de IFGe, el laboratorio debe validar su procedimiento analítico para determinar creatinina. El Error Total no debe superar el 8% para que no produzca un aumento mayor del 10% en la estimación del IFG. Para la detección de ERC se recomienda: 1) Estimar la VFG utilizando la ecuación MDRD-4 asociada a Crp (fuerza de recomendación C). 2) Informar valores de más de 60 mL/min/1,73 m² sólo como "mayor de 60" y los valores menores de 60, como el número exacto obtenido; 3) Excluir en sistemas con cálculos automáticos las situaciones que limitan el uso de la ecuación.

The increase in prevalence of patients with Chronic Kidney Disease (CKD) has turned it a worldwide public health problem not only due to its requirement of a kidney replaceable treatment, but also because cardiovascular disease is now the main cause of death among these patients. Plasma Creatinine (Crp) is not always an early marker, due to the fact that its blood levels exceed the highest limit of the reference range when the Glomerular Filtration Rate (GFR) decreases to a half. GFR measurement with exogenous markers is the best indicator to test renal function (RF), although its use in the clinical practice is only restricted to special situations. Creatinine Clearance (CC) may have errors caused by an inadequate urine collection. Moreover, it overestimates the GFR considering that creatinine is not only excreted but also secreted at the tubular level. The utilization of formulas associated to Crp is recommended by most of the Scientific Societies. The MDRD-4 equation has been adopted by consensus "eGFR (mL/min/1.73 m²)= 186 x (Crp) -1.154 x (age) -0.203 x (0.742 woman) x (1.212 black people)". When the creatinine results are traceable to isotope Dilution/Mass Spectrometry reference method, the initial factor is 175. This formula does not apply to pregnant women, hospitalized patients, people under 18 or older than 70 years old, amputees, etc. Given that the measurement of Crp is the biggest cause of error for the calculation of eGFR, the lab should validate the analytical procedure to determine creatinine. The Total Error should not exceed 8% in order not to yield an increase over 10% of GFR estimation. For CKD detection, it is recommended as follows: 1) Estimate the GFR using MDRD-4´s equation associated to Crp. (Strength of Recommendation C); 2) Report values over 60 mL/min/1.73 m² only as "over 60" and values under 60 as the exact number obtained; 3) Exclude from automatic calculation systems, situations that limit the use of the equation.

Recomendações atuais para a detecção da nefropatia diabética / Guidelines for the detection of diabetic nephropathy

A nefropatia diabética (ND) é uma complicação crônica grave do diabetes melito (DM); é a principal causa de insuficiência renal terminal. A ND é classificada em 3 estágios conforme a excreção urinária de albumina (EUA): normoalbuminúria (EUA <17 mg/l), microalbuminúria (EUA 17-174 mg/l) e macroalbuminúria (>174 mg/l). Da fase de microalbuminúria pode ocorrer regressão para normoalbuminúria (30% casos) ou progressão para a macroalbuminúria, quando ocorre maior risco de evolução para a doença renal crônica (DRC) terminal. O diagnóstico da ND é realizado através da medida da albumina na urina e pela avaliação da taxa de filtração glomerular (TFG). Recomenda-se a medida da albumina em amostra isolada de urina (primeira da manhã ou amostra casual), podendo-se medir o índice albumina-creatinina ou a concentração de albumina. Valores elevados de albuminúria devem ser confirmados em pelo menos 2 de 3 coletas de urina, em um intervalo de 3 a 6 meses. Na impossibilidade da medida da albuminúria, a medida de proteínas totais (proteinúria @430 mg/l em amostra ou >500 mg/24 h), pode ser utilizada para diagnóstico de fases mais avançadas de ND. Em pacientes com DM tipo 2 o rastreamento deve iniciar ao diagnóstico de DM, e nos pacientes com DM tipo 1 deve ser após os 10 anos de idade; logo após o início da puberdade; ou quando a duração do DM for >5 anos. Se negativo repetir anualmente; e, se positivo, recomenda-se a monitoração mais frequente da albumina urinária. A estimativa da TFG é realizada através de fórmulas que empregam a creatinina sérica, ajustadas para idade, gênero e etnia. São recomendadas as equações do estudo Modification of Diet in Renal Disease (MDRD) e Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI). Deve ser levado em conta que, em pacientes com DM, essas equações tendem a subestimar a TFG. A ND deve ser identificada o mais precocemente possível e para isto tanto os profissionais de saúde como os pacientes com DM devem ser conscientizados.

Diabetic nephropathy (DN) is an important chronic complication of diabetes mellitus (DM) and is the leading cause of end-staage renal disease. DN is classified into stages according to the urinary albumin excretion (UAE): normoalbuminuria (UAE <17 mg/l), microalbuminuria (UAE 17-174 mg/l), and macroalbuminuria (UAE >174 mg/l. From microalbuminuria there might be regression to normoalbuminuria (30% cases) or progression to macroalbuminuria, in which case there is higher risk of progression to advanced chronic kidney disease (CKD). DN has a high cardiovascular morbidity and mortality rate that is possibly more significant than the progression to terminal CKD. DN diagnosis is established by the measurement of albumin in the urine and assessment of glomerular filtration rate (GFR). The measurement of albumin in an isolated urine sample (first morning urine or random sample) is recommended, with the possibility of measuring albumin-creatinine ratio or albumin concentration. High levels of albuminuria should be confirmed by at least 2 out of 3 urine samples within a time interval of 3 to 6 months. If albuminuria cannot be measured, total protein level (proteinuria @ 430 mg/l in a sample or > 500 mg/24 h) can be used to diagnose advanced stages of DN. In patients with type 2 DM, screening should start upon diagnosis of DM, and in patients with type 1 DM, it should be started after the patient turns 10 years old; soon after the onset of puberty; or when the duration of DM is >5 years. In case of negative results, screening should be repeated annually and, if the result is positive, more frequent monitoring of urinary albumin is recommended. GFR estimation is calculated using formulas that employ serum creatinine adjusted for age, gender, and ethnicity. Modification of Diet in Renal Disease (MDRD) study and CKD-EPI (Chronic Kidney Disease - Epidemiology Collaboration) equations are the recommended. In patients with DM, this equation shows a tendency to underestimate GFR.

Calibração da creatinina sérica com uso de equação de regressão: influência na performance da fórmula do estudo MDRD / Serum creatinine calibration with regression equation: influence on MDRD formula performance

Diferenças nos métodos de medida da creatinina sérica podem determinar amplas variações na taxa de filtração glomerular (TFG) estimada com fórmulas. Para a padronização da medida da creatinina, deve ser usado método calibrado rastreável para medida de referência com ID-MS (isotope dilution mass spectrometry). Objetivo: Avaliar a TFG estimada com a equação MDRD (Modification of Diet in Renal Disease) original (MDRDo, creatinina método não calibrado) e a equação MDRD re-expressa (MDRDr, método calibrado por ID-MS), comparando-as com a TFG medida pelo 51Cr-EDTA (método padrão) em indivíduos normais. Métodos: Foram avaliados 101 indivíduos, com idade média de 38±12 anos, sendo 45 homens. A TFG foi medida pela técnica de injeção única do 51Cr-EDTA (TFG 51Cr-EDTA) e estimada pelas equações MDRDo: 186 x creatinina sérica-1,154 x idade-0,203 x 0,742 (se mulher) x 1,210 (se negro) e MDRDr, substituindo-se o valor 186 por 175 na equação. A creatinina sérica foi medida pelo método de Jaffe não calibrado e transformada em calibrado com a fórmula: y=1,07x-0,249, obtida previamente por regressão. A concordância entre os métodos foi avaliada através da análise de Bland&Altman. Resultados: Os valores médios para as TFG 51Cr-EDTA, MDRDr e MDRDo foram de 105±18, 102±21 e 84±13 ml/min/1,73 m², respectivamente. Acurácia (percentual de casos de TFG estimada que não desviam em mais de 15% do valor medido) foi maior com o uso da MDRDr em relação à MDRDo (57% vs. 35%, P=0,002). O viés (diferença entre TFG medida e estimada) para 51Cr-EDTA e MDRDr foi de 3±23 ml/min/1,73 m². Para 51Cr-EDTA e MDRDo o viés foi significativamente maior, sendo de 21±18 ml/min/1,73 m². No entanto, a precisão, avaliada como desvio padrão do viés indicou elevada dispersão nos dois casos. Conclusão: O uso da equação re-expressa do MDRD, empregando a creatinina calibrada, produz uma estimativa mais acurada da TFG do que a equação original do MDRD.

Differences in methods of measurement of serum creatinine may provide wide variations in glomerular filtration rate (GFR) estimated with formulas. To standardize the measurement of creatinine, calibrated methods should be used, traceable to the reference ID-MS (isotope dilution mass spectrometry) method. Aim: To evaluate the performance of GFRs estimated with the original Modification of Diet in Renal Disease study equation (MDRDo; non-calibrated creatinine method) and with the re-expressed MDRD equation (MDRDr; ID-MS creatinine), comparing them with the GFR measured by 51Cr-EDTA (standard method ) in normal adults. Methods: 101 subjects, aged 38±12 years, 45 (45%) men were evaluated. GFR was measured by single-injection 51Cr-EDTA (GFR 51Cr-EDTA) technique and estimated by the following equations - MDRDo: 186 x serum creatinine-1. 154 x age-0.203 x 0.742 (if female) x 1.210 (if black), and MDRDr, replacing the value 186 by 175 in the equation. Serum creatinine was measured by a non-calibrated Jaffe’s method and transformed into calibrated with the formula: y=1.07x-0.249, previously obtained by regression. The agreement between methods was assessed by the Bland&Altman analyses. Results: The mean GFR 51Cr-EDTA, MDRDr and MDRDo were 105±18, 102±21 and 84±13 ml/min/1, 73 m2, respectively. There was no agreement between 51Cr-EDTA and MDRDo GFR (P <0.001), but it was present between 51Cr-EDTA and MDRDr GFR (P=0.149). Accuracy (percentage of cases of estimated GFR within 15% of measured value) was higher with the use of MDRDr in comparison to MDRDo (57% vs. 35%, P=0.002). Bias (diference between measured and estimated GFR) for 51Cr-EDTA and MDRDr was 3±23 ml/min/1.73 m². For 51Cr-EDTA and MDRDo the bias was significantly higher, 21±18 ml/min/1.73 m². However, the precision, evaluated as standard deviation of bias indicated a huge variation in both cases. Conclusion: The re-expressed MDRD equation, using calibrated creatinine, is a more accurate estimation of GFR than.

Detecção precoce da nefropatia diabética / Early detection of diabetic nephropathy

Em virtude do prognóstico desfavorável das fases avançadas da nefropatia diabética (ND), o ideal é identificar o envolvimento renal de maneira precoce. A recomendação é a medida anual da excreção urinária de albumina (EUA), em amostras de urina casual, para detectar os estágios da ND [microalbuminúria (EUA 17-174 mg/l ou 30 a 300 mg albumina/g de creatinina) e macroalbuminúria (> 174 mg/l ou > 300 mg/g)]. No entanto, tem sido sugerido que níveis de EUA abaixo dos de consenso já seriam indicativos de risco de progressão renal e de mortalidade aumentada, devendo ser revisados esses pontos de corte. Uma quantidade expressiva da EUA, a fração não imunorreativa, não é detectada pelos métodos convencionais, e HPLC poderá ser mais sensível para identificar dano renal, medindo EUA total (imuno + não-imunorreativa). Outra observação recente é a presença de diminuição da taxa de filtração glomerular (TFG) mesmo em normoalbuminúricos. Portanto, além da EUA, recomenda-se estimar a TFG com equação empregando creatinina, como a do estudo Modification of Diet in Renal Disease (MDRD), disponível em www.mdrd.com. Em razão das conhecidas limitações da creatinina, marcadores endógenos alternativos estão em investigação, sendo a cistatina C um marcador promissor. Finalmente, novas estratégias que poderão ser ainda mais precoces para detecção da ND incluem biomarcadores, como proteoma, definindo um perfil de proteínas urinárias que identifiquem risco subseqüente de doença renal.

Due to the unfavorable prognosis of advanced stages of diabetic nephropathy (DN), the ideal approach is to identify renal involvement as early as possible. It is recommended to measure urinary albumin excretion (UAE) annually, in random urine samples, in order to detect the stages of DN [microalbuminuria (UAE 17-174 mg/l or 30-300 mg albumin/g of creatinine) and macroalbuminuria (> 174 mg/l or > 300 mg/g)]. However, it has been suggested that UAE levels below the threshold of consensus could already signal the risk for DN progression and increased mortality, indicating the need to revise cutoff values. As a substantial amount of UAE (the immunounreactive fraction), is not detected by conventional methods, HPLC would be more sensitive to identify the presence of damage by measuring total UAE (immunoreactive + immunounreactive). Another recent observation is that diminished glomerular filtration rates (GFR) occurs in the presence of normoalbuminuria. Therefore, besides evaluating UAE, it is recommended to estimate GFR with equations employing creatinine; such as the Modification of Diet in Renal Disease (MDRD) study, available at www.mdrd.com. Owing to the known limitations of creatinine, alternative endogenous markers are being studied, and cystatin-C is a promising marker under investigation. Finally, new strategies that could detect DN even earlier, include biomarkers such as proteomics, defining a profile of urinary protein excretion able to identify the subsequent risk of renal disease.