Valoración del uso del índice ictérico como parámetro para la gestión de la determinación de la bilirrubina total / Use of icteric index as a parameter for the management of the determination of total bilirubin

Introducción: El exceso de pruebas enviadas al laboratorio, en numerosas ocasiones, no aporta un valor añadido, lo que nos lleva a plantearnos su uso eficiente. La bilirrubina es una magnitud bioquímica clásica para el estudio de la alteración hepática, y el índice ictérico es una medida indirecta para la determinación semicuantitativa de la bilirrubina. Objetivos: Evaluar la utilidad del índice ictérico para detectar a pacientes con concentraciones de bilirrubina en suero superiores o inferiores a 1,20mg/dL, de manera que interese valorar la determinación de bilirrubina, y calcular el ahorro que supondría la aplicación de este algoritmo. Material y métodos: Se realizó un estudio retrospectivo para determinar la correlación entre el índice ictérico y la bilirrubina, y un análisis de regresión. La eficacia diagnóstica del índice ictérico se estudió mediante una curva Receiver Operating Characteristic, determinando el valor de corte del índice ictérico que permite discriminar valores de bilirrubina superiores e inferiores a 1,20mg/dL. Se calculó la sensibilidad, especificidad, valor predictivo positivo y valor predictivo negativo. Resultados y discusión: El análisis estadístico indicó una buena correlación entre ambas variables. El estudio de eficacia diagnóstica mostró que el punto de corte índice ictérico=2 tiene un alto valor predictivo negativo y una alta sensibilidad y especificidad. Conclusiones: Los valores de índice ictérico correlacionan bien con la bilirrubina, permitiendo el cribado de la hiperbilirrubinemia. Así se evitaría realizar el 89,72% de las bilirrubinas, informándose como<1,20mg/dL aquellas muestras con índice ictérico≤1, suponiendo un ahorro importante al laboratorio

Introduction: As too many laboratory tests may not represent significant improvements, their efficient use should be considered. Bilirubin is a classical biochemical marker of hepatic alterations, and the icteric index is an indirect measure for the semi-quantitative determination of jaundice. Objectives: To evaluate the use of the icteric index in the identification of patients with serum bilirubin concentrations with values higher or lower than 1.20mg/dL, as well as to assess the determination of bilirubin, and to evaluate the savings that the application of this algorithm would represent. Material and methods: A retrospective study was performed to determine the relationship between icteric index and total bilirubin. A regression analysis was also performed. The diagnostic efficiency of the index was studied using a Receiver Operating Characteristic curve to determine the cut-off value that would allow to distinguish bilirubin values higher and lower than 1.20mg/dL. The sensitivity and specificity, positive predictive value and negative predictive value were also calculated. Results and discussion: The statistical analysis showed a high correlation between both variables. The study of diagnostic efficacy showed that to use an icteric index equal to 2 as a cut-off point yields a high negative predictive value, sensitivity and specificity. Conclusions: Icteric index values are well correlated with bilirubin, which allows filtering for hyperbilirubinaemia. Therefore, 89.72% of bilirubin requests would not be needed. With those samples with icteric index ≤ 1 subsequently being reported as<1.20mg/dL, thus representing a savings to the laboratory

Tirotoxicosis en paciente con enfermedad trofoblástica gestacional. A propósito de un caso / Hyperthyroidism in metastatic gestational trophoblastic disease. A case report

La gonadotropina coriónica humana (hCG) es producida por el trofoblasto tanto en el embarazo como en la enfermedad trofoblástica gestacional (ETG). La subunidad α de la hCG es idéntica a las subunidades α de otras hormonas, como hormona luteinizante (LH), la hormona folículo estimulante (FSH) y la hormona estimulante de la tiroides (TSH). Una elevación marcada de hCG se asocia a la presencia de complicaciones como la hiperémesis gravídica, el desarrollo precoz de preeclampsia y, ocasionalmente, con el hipertiroidismo. Los procedimientos de laboratorio utilizados para la medición de los niveles de hCG son bastante sensibles y específicos para el estudio de las condiciones del trofoblasto (AU)

Human chorionic gonadotropin (hCG) is produced by trophoblasts in pregnancy as well as in gestational trophoblastic diseases (GTD). The alpha subunit is identical to that for luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH). Elevated serum levels of hCG can lead to complications that include hyperemesis gravidarum, early development of preeclampsia, and occasionally hyperthyroidism. Laboratory test for hCG are very sensitive and specific (AU)

[Impact of the weather on the serum levels of prostatic specific antigen (PSA)]. / Impacto de la climatología sobre el nivel sérico de antígeno especifico prostático (PSA).

OBJECTIVES: To analyze the impact of season and weather parameters on serum PSA values in men without prostate cancer. METHODS: Retrospective study including medical records from the Spanish arm of the European Randomized Study of Screening for Prostate Cancer (ERSPC). EXCLUSION CRITERIA: prostate cancer diagnosis, PSA > = 10 ng/ml, or PSA > = 3 ng/ml and/or digital rectal examination abnormalities unless a negative prostate biopsy was provided. Univariate relationships between PSA value, season and several weather parameters were assessed. A multivariate logistic regression model was used to identify independent predictors of a PSA value > = 3 ng/ml. RESULTS: A total of 2,147 men entered into the study. Median age and PSA level were 57 years and 0.9 ng/ml respectively. A non-significant trend to higher PSA levels was observed during autumn and winter. Multivariate logistic regression analysis identified only maximum temperature (p < 0.001), minimum temperature (p = 0.001) and age (p < 0.001) as independent predictors of a PSA value > = 3 ng/ml. Mean age-adjusted PSA levels at maximum temperatures of < = 15 degrees C, 16-20 degrees C, 21-25 degrees C and > =26 degrees C were 1.25, 1.20, 1.17 and 1.09 ng/ml respectively. CONCLUSIONS: PSA levels are slightly higher during cold weather conditions. Because of the small magnitude of this PSA increment we do not recommend to change biopsy indication based solely on climatic parameters.

Impacto de la climatología sobre el nivel sérico de antígeno específico prostático (PSA) / Impact of the weather on the serum levels of prostatic specific antigen (PSA)

OBJETIVO: Analizar el impacto de la estación climática y de ciertos parámetros meteorológicos sobre el nivel de PSA sérico en varones sin cáncer de próstata. MÉTODOS: Estudio retrospectivo que incluye registros de la rama Española del European Randomized Study of Screening for Prostate Cancer (ERSPC). Los criterios de exclusión fueron el diagnóstico de cáncer de próstata, presentar PSA >= 10 ng/ml, o bien PSA >= 3 ng/ml y/o anomalías en el tacto rectal a menos que se disponga de una biopsia prostática negativa para malignidad. Se investigó la relación univariante entre nivel de PSA y estación climática, así como varios parámetros meteorológicos. Se empleó un modelo multivariante de regresión logística para identificar predictores independientes de la obtención de un nivel de PSA >=3 ng/ml. RESULTADOS: Un total de 2.147 varones fueron incluidos en el estudio. Las medianas de edad y PSA fueron 57 años y 0,9 ng/ml respectivamente. Se observó una tendencia no significativa hacia niveles de PSA más elevados durante las estaciones de otoño e invierno. El modelo multivariante de regresión logística identificó únicamente las temperaturas máxima (p= 3 ng/ml. Los niveles medios de PSA ajustado a la edad en los rangos de temperatura máxima =26ºC fueron 1,25, 1,20, 1,17 y 1,09 ng/ml respectivamente. CONCLUSIONES: Los niveles de PSA sérico son ligeramente más elevados durante condiciones de frío climático. Debido a la pequeña magnitud de esta elevación, no recomendamos cambiar la indicación de biopsia prostática basándonos únicamente en factores climáticos

OBJECTIVES: To analyze the impact of season and weather parameters on serum PSA values in men without prostate cancer. METHODS: Retrospective study including medical records from the Spanish arm of the European Randomized Study of Screening for Prostate Cancer (ERSPC). Exclusion criteria: prostate cancer diagnosis, PSA >= 10 ng/ml, or PSA >= 3 ng/ml and/or digital rectal examination abnormalities unless a negative prostate biopsy was provided. Univariate relationships between PSA value, season and several weather parameters were assessed. A multivariate logistic regression model was used to identify independent predictors of a PSA value >=3 ng/ml. RESULTS: A total of 2,147 men entered into the study. Median age and PSA level were 57 years and 0.9 ng/ml respectively. A non-significant trend to higher PSA levels was observed during autumn and winter. Multivariate logistic regression analysis identified only maximum temperature (p= 3 ng/ml. Mean age-adjusted PSA levels at maximum temperatures of =26ºC were 1.25, 1.20, 1.17 and 1.09 ng/ml respectively. CONCLUSIONS: PSA levels are slightly higher during cold weather conditions. Because of the small magnitude of this PSA increment we do not recommend to change biopsy indication based solely on climatic parameters

[Measurement of minimum disposable volume in the extraction of an analysis through an arterial catheter]. / Determinación del volumen mínimo desechable en laextracción de una analítica a través de un catéter arterial.

OBJECTIVE: Arterial catheters are used to extract blood samples. To maintain its permeability we use heparin solution, which may contaminate and alter the desired results. Our aim was to determine the volume of the minimum discards during blood extractions to avoid results that might be altered in the analysis of biochemistry. MATERIAL AND METHODS: A prospective study was carried out in 18 beds intensive care unit. Patients with arterial catheter (Seldicath) were included, maintaining 500 UI of heparin in saline of 500 ml, at a pressure of 300 mmHg through pressurizer (Tycos). The dead space (DS) in the radial arterial system is 0.8 ml and 1 ml in the femoral. We analyzed the reliability of different discards comparing the following: 3 ml + DS, 7.5 ml + DS, 12 ml + DS and 16.5 ml + DS. The statistical analysis was carried out through ANOVA and t Student. RESULTS: In biochemistry, significant differences were not found except for potasium (p< 0.001) with 3 ml+DS during control, although it is not clinically relevant [difference through = 0.1 mEq/l (DS 0.2)]. Significant differences in prothrombina (p = 0.004) were found in coagulation, comparing 3 ml+DS and 16.5 ml + DS and in cefaline, comparing 7.5 ml + DS (p< 0.0001) and 16.5 ml + DS. There were not significant differences in the studies of gases. CONCLUSIONS: Our study shows that to reach a reliable analytical results, it is not necessary to discard more than 3 ml+DS in biochemistry and in blood gases, and to determine cefalina time would necessary to discard a minimum of 7.5 ml+DS.