Identification and validation of biomarkers of persistent acute kidney injury: the RUBY study.

PURPOSE: The aim of the RUBY study was to evaluate novel candidate biomarkers to enable prediction of persistence of renal dysfunction as well as further understand potential mechanisms of kidney tissue damage and repair in acute kidney injury (AKI). METHODS: The RUBY study was a multi-center international prospective observational study to identify biomarkers of the persistence of stage 3 AKI as defined by the KDIGO criteria. Patients in the intensive care unit (ICU) with moderate or severe AKI (KDIGO stage 2 or 3) were enrolled. Patients were to be enrolled within 36 h of meeting KDIGO stage 2 criteria. The primary study endpoint was the development of persistent severe AKI (KDIGO stage 3) lasting for 72 h or more (NCT01868724). RESULTS: 364 patients were enrolled of whom 331 (91%) were available for the primary analysis. One hundred ten (33%) of the analysis cohort met the primary endpoint of persistent stage 3 AKI. Of the biomarkers tested in this study, urinary C-C motif chemokine ligand 14 (CCL14) was the most predictive of persistent stage 3 AKI with an area under the receiver operating characteristic curve (AUC) (95% CI) of 0.83 (0.78-0.87). This AUC was significantly greater than values for other biomarkers associated with AKI including urinary KIM-1, plasma cystatin C, and urinary NGAL, none of which achieved an AUC > 0.75. CONCLUSION: Elevated urinary CCL14 predicts persistent AKI in a large heterogeneous cohort of critically ill patients with severe AKI. The discovery of CCL14 as a predictor of persistent AKI and thus, renal non-recovery, is novel and could help identify new therapeutic approaches to AKI.

Unmeasurable severe hypernatremia: A different way of using the calculated serum osmolality formula / Hipernatremia incalculable severa: una manera diferente de utilizar la fórmula de osmolaridad sérica

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The use of cell cycle arrest biomarkers in the early detection of acute kidney injury. Is this the new renal troponin? / El uso de biomarcadores de detección del ciclo celular para el diagnóstico precoz del fracaso renal agudo. ¿La nueva troponina renal?

Acute kidney injury (AKI) has a high prevalence in critical care patients. Early detection might prevent patients from developing chronic kidney disease and requirement for renal replacement therapy. If we compare AKI with acute coronary syndrome, in which an increase in cardiac troponin may trigger early diagnosis and therapeutic intervention, we could extrapolate a similar technique in patients with early AKI without changes in urinary frequency or serum creatinine. The objective is to identify biomarker-positive, creatinine-negative patients that would allow therapeutic interventions to be initiated before finding changes in serum creatinine, preventing kidney damage. Tissue inhibitor of metalloproteinase 2 and insulin-like growth factor binding protein 7 are cell cycle arrest biomarkers that have demonstrated, in recent clinical trials, to have good sensitivity and specificity for early detection of AKI. Other recent studies have shown that the joint use of these biomarkers with serum creatinine and urine production could improve the prognosis of AKI in critical patients. The application of these biomarkers in clinical practice would enable the early identification of patients at risk of AKI, establishing interventions that would improve the survival of renal function

Existe una gran prevalencia del fracaso renal agudo (FRA) en pacientes críticos. La detección temprana prevendría el desarrollo de la enfermedad renal crónica y el requerimiento de terapias renales de sustitución. Si comparamos el FRA con el síndrome coronario agudo, en el que el uso de la troponina cardiaca permite el diagnóstico precoz y su consecuente terapia, se podría extrapolar técnica similar en pacientes con FRA temprano sin cambios en la frecuencia urinaria o creatinina sérica. El objetivo sería identificar a pacientes con un biomarcador positivo y la creatinina negativa que permitiera iniciar intervenciones terapéuticas antes de objetivar cambios en la creatinina sérica, previniendo el daño renal. El inhibidor tisular de metaloproteinasa-2 y la proteína de enlace 7 del factor de crecimiento insulínico, son biomarcadores de detención del ciclo celular, que han demostrado, en estudios recientes, tener adecuada sensibilidad y especificidad para la pronta identificación del FRA. Otros estudios recientes han mostrado que el uso conjunto de estos biomarcadores con la creatinina sérica y la producción de orina, pudieran mejorar el pronóstico del FRA en pacientes críticos. La aplicación de estos biomarcadores en la práctica clínica permitiría la identificación precoz de pacientes con riesgo de FRA estableciendo intervenciones que mejorarían la supervivencia de la función renal

The use of cell cycle arrest biomarkers in the early detection of acute kidney injury. Is this the new renal troponin?

Acute kidney injury (AKI) has a high prevalence in critical care patients. Early detection might prevent patients from developing chronic kidney disease and requirement for renal replacement therapy. If we compare AKI with acute coronary syndrome, in which an increase in cardiac troponin may trigger early diagnosis and therapeutic intervention, we could extrapolate a similar technique in patients with early AKI without changes in urinary frequency or serum creatinine. The objective is to identify biomarker-positive, creatinine-negative patients that would allow therapeutic interventions to be initiated before finding changes in serum creatinine, preventing kidney damage. Tissue inhibitor of metalloproteinase 2 and insulin-like growth factor binding protein 7 are cell cycle arrest biomarkers that have demonstrated, in recent clinical trials, to have good sensitivity and specificity for early detection of AKI. Other recent studies have shown that the joint use of these biomarkers with serum creatinine and urine production could improve the prognosis of AKI in critical patients. The application of these biomarkers in clinical practice would enable the early identification of patients at risk of AKI, establishing interventions that would improve the survival of renal function.

Common chronic conditions do not affect performance of cell cycle arrest biomarkers for risk stratification of acute kidney injury.

BACKGROUND: Identification of acute kidney injury (AKI) can be challenging in patients with underlying chronic disease, and biomarkers often perform poorly in this population. In this study we examined the performance characteristics of the novel biomarker panel of urinary tissue inhibitor of metalloproteinases-2 (TIMP2) and insulin-like growth factor-binding protein 7 ([IGFBP7]) in patients with a variety of comorbid conditions. METHODS: We analyzed data from two multicenter studies of critically ill patients in which [TIMP2]•[IGFBP7] was validated for prediction of Kidney Disease: Improving Global Outcomes (KDIGO) Stage 2 or 3 AKI within 12 h. We constructed receiver operating characteristic (ROC) curves for AKI prediction both overall and by comorbid conditions common among patients with AKI, including diabetes mellitus, congestive heart failure (CHF) and chronic kidney disease (CKD). RESULTS: In the overall cohort of 1131 patients, 139 (12.3%) developed KDIGO Stage 2 or 3 AKI. [TIMP2]•[IGFBP7] was significantly higher in AKI versus non-AKI patients, both overall and within each comorbidity subgroup. The AUC for [TIMP2]•[IGFBP7] in predicting AKI was 0.81 overall. Higher AUC was noted in patients with versus without CHF (0.89 versus 0.79; P = 0.026) and CKD (0.91 versus 0.80; P = 0.024). CONCLUSIONS: We observed no significant impairment in the performance of cell cycle arrest biomarkers due to the presence of chronic comorbid conditions.

IgA-dominant post-infectious glomerulonephritis; making another case in support of renal biopsy in type 2 diabetic nephropathy.

BACKGROUND: Approximately one-third of individuals with type 2 diabetes mellitus will eventually develop diabetic nephropathy (DN). Impaired renal function in type 2 diabetics may also be secondary to non-diabetic renal disease (NDRD). NDRD in type 2 diabetics may occur alone in the absence of DN or may be superimposed on DN. Renal biopsy maybe indicated to establish the correct diagnosis and to ascertain the severity of glomerular and tubulointerstitial pathology. CASE: We report a patient with type 2 diabetes mellitus and chronic renal insufficiency who developed worsening of renal function in the setting of staphylococcal infection and antibiotic use. CONCLUSION: Renal biopsy revealed IgA-dominant post-infectious glomerulonephritis and acute interstitial nephritis superimposed on diabetic glomerulosclerosis. Accumulating evidence indicates that, NDRD accounts for impaired renal function in a significant number of patients with type 2 diabetes mellitus. The presence of clinical, biochemical, and radiological features that suggest NDRD should prompt pathological evaluation of the kidney.

Use of Extracorporeal Techniques in the Removal of Dabigatran.

Dabigatran is a novel direct thrombin inhibitor that has proven effective in the prevention of vascular events in patients with nonvalvular atrial fibrillation. Not much is known about the clearance capability with extracorporeal techniques of dabigatran. This review showcases the pharmacokinetics and a perusal of the current literature regarding cases that involved the clearance of the drug in patients with normal renal function and end-stage renal disease. Renal replacement therapy represents a therapeutic option to eliminate dabigatran and decreased the risk of bleeding in patients undergoing emergent surgical procedures on dabigatran.

Hypertension in the African American population: A succinct look at its epidemiology, pathogenesis, and therapy.

Arterial hypertension is prevalent in the black population in the United States. It is directly related to cardiovascular and kidney damage. Its pathogenesis is complex and includes the high incidence of obesity, salt sensitivity and the activation of the renin-angiotensin-aldosterone system. This complexity requires a therapeutic combination that includes changes in dietary habits and appropriate antihypertensive regimes. The International Society of Hypertension in Blacks recommends initiating dietary intervention for values of systolic/diastolic arterial blood pressure above 115/75 mmHg and maintaining arterial blood pressure below 135/85 mmHg using appropiate antihypertensive medication. The most adequate antihypertensive drug for this population has yet to be determined.

Hypertension in the African American population: A succinct look at its epidemiology, pathogenesis, and therapy / Hipertensión en la población afroamericana: breve examen de su epidemiología, patogénesis y terapia

Arterial hypertension is prevalent in the black population in the United States. It is directly related to cardiovascular and kidney damage. Its pathogenesis is complex and includes the high incidence of obesity, salt sensitivity and the activation of the renin-angiotensinal dosteronesystem. This complexity requires a therapeutic combination that includes changes in dietary habits and appropriate antihypertensive regimes. The International Society of Hypertension in Blacks recommends initiating dietary intervention for values of systolic/diastolic arterial blood pressure above 115/75 mmHg and maintaining arterial blood pressure below 135/85 mmHg using appropiate antihypertensive medication. The most adequate antihypertensive drug for this population has yet to be determined (AU)

La hipertensión arterial es prevalente en la población de raza negra en los EEUU. Presenta una relación directa con el daño cardiovascular y renal. Su patogenia es compleja e incluye la alta incidencia de obesidad, sensibilidad a la sal, y la consecuente activación del sistema de la renina, angiotensina y aldosterona. Eso hace que requiera una combinación terapéutica que incluye cambios dietéticos y regímenes antihipertensivos adecuados. La Sociedad internacional de la hipertensión en pacientes de raza negra recomienda iniciar dietas de control para valores de tensión arterial sistólica/diastólica por encima de los 115/75 mmHg y mantener una tensión arterial por debajo de 135/85 mmHg con el uso de medicación antihipertensiva idónea. El fármaco antihipertensivo adecuado está por determinar en esta población (AU)

Crystal-induced acute kidney injury due to ciprofloxacin.

BACKGROUND: Fluoroquinolones are known to cause acute renal failure due to interstitial nephritis. CASE PRESENTATION: Here we present an elderly woman who developed oliguric acute kidney injury (AKI) after receiving oral and intravenous ciprofloxacin in a 48-hour period. Recently, several case reports have been published in the literature regarding the presence of crystals in the urine sediment of patients treated with ciprofloxacin for different types of systemic infections. Ciprofloxacin crystals precipitate in alkaline urine and provoke renal failure through intra-tubular precipitation. CONCLUSIONS: Conservative measures including intravenous hydration and avoidance of alkalinization of the urine can reverse this condition if applied in time.

Contrast-induced nephropathy: pathogenesis and new therapeutic options for prevention.

Contrast-induced nephropathy is a common cause of inpatient and outpatient acute renal failure. The pathogenesis is complex adding difficulty to its management. Several preventive measures that involved the use of intravenous fluids and oral agents have been implemented in human studies with heterogeneous results because of the disparity in defining changes in glomerular filtration rate after renal injury. New preventive techniques based on the pathogenesis of contrast-induced nephropathy are being applied to human subjects with preliminary good outcomes. Future randomized trials will give us the opportunity to elucidate its benefits.

Anti-GBM disease and ANCA during dengue infection.

Anti-glomerular basement membrane (GBM) disease is a severe inflammatory renal disorder due to pathogenic autoantibodies directed mainly against the α3 chain of type IV collagen. In ~1/4 of patients with anti-GBM disease, antineutrophil cytoplasmic antibodies (ANCA) predominantly with myeloperoxidase (MPO) specificity can be detected. Although the inciting stimuli leading to the development of an immune response against the type IV collagen and neutrophils are unknown, evidence indicates that both genetic and environmental factors play a role. Of note, molecular mimicry between self-antigens and nonself-antigens such as antigenic determinants of microorganisms has been implicated in the pathogenesis of anti-GBM disease and ANCA-associated vasculitis. A mosquito-borne viral illness highly prevalent in the tropics and subtropics, dengue can be complicated by acute renal failure, proteinuria, hematuria and glomerulonephritis. We present a 66-year-old woman who was diagnosed with dengue infection and rapidly progressive glomerulonephritis during an outbreak of dengue in Honduras in the summer of 2013. Renal biopsy revealed severe crescentic glomerulonephritis. Immunofluorescence examination demonstrated strong linear IgG deposition along glomerular capillary walls. Serologic tests demonstrated antibodies against GBM, MPO and platelet glycoproteins. The patient was diagnosed with anti-GBM disease associated with p-ANCA with MPO specificity. Despite heavy immunosuppression and plasmapheresis, IgG titers against dengue virus continued to rise confirming the diagnosis of acute dengue infection. We present the first reported case of anti-GBM disease associated with p-ANCA with MPO specificity during dengue infection. This report calls for a heightened awareness of autoimmunity leading to crescentic glomerulonephritis in patients with dengue infection.

Necrotizing crescentic glomerulonephritis in a patient with positive serologies for lupus and antineutrophil cytoplasmic antibodies

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Catastrophic antiphospholipid syndrome: a clinical review.

CONTEXT: Catastrophic antiphospholipid syndrome (CAPS) is a rare life-threatening autoimmune disease characterized by disseminated intravascular thrombosis resulting in multiorgan failure. EVIDENCE ACQUISITIONS: Directory of Open Access Journals (DOAJ), Google Scholar, PubMed (NLM), LISTA (EBSCO) and Web of Science have been searched. RESULTS: CAPS is due to antiphospholipid antibodies directed against a heterogeneous group of proteins that are associated with phospholipids. These autoantibodies activate endothelial cells, platelets, and immune cells, thereby promoting a proinflammatory and prothrombotic phenotype. Furthermore, antiphospholipid antibodies inhibit anticoagulants, impair fibrinolysis, and activate complements. Although CAPS can affect a variety of organs and tissues, the kidneys, lungs, central nervous system, heart, skin, liver, and gastrointestinal tract are most commonly affected. The systemic inflammatory response syndrome, likely to extensive tissue damage, accompanies CAPS. The most frequent renal manifestations are hypertension, proteinuria, hematuria, and acute renal failure.In the majority of patients with CAPS, a precipitating factor such as infection, surgery, or medication can be identified. Antiphospholipid antibodies such as lupus anticoagulant and antibodies against cardiolipin, ß2-glycoprotein I, and prothrombin are serological hallmark of CAPS. Laboratory tests often reveal antinuclear antibodies, thrombocytopenia, and anemia. Despite widespread intravascular coagulation, blood films reveal only a small number of schistocytes. In addition, severe thrombocytopenia is uncommon. CONCLUSIONS: Histologically, CAPS is characterized by acute thrombotic microangiopathy. CAPS must be distinguished from other forms of thrombotic microangiopathies such as hemolytic-uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation, and heparin-induced thrombocyt openia. CAPS is associated with high morbidity and mortality. Therefore, an aggressive multidisciplinary treatment strategy is indicated. Anticoagulation, immunosuppression, plasma exchange, intravenous immunoglobulins, and anti-platelet agents, used in various combinations, have resulted in improved patient outcome.

Validation of cell-cycle arrest biomarkers for acute kidney injury using clinical adjudication.

RATIONALE: We recently reported two novel biomarkers for acute kidney injury (AKI), tissue inhibitor of metalloproteinases (TIMP)-2 and insulin-like growth factor binding protein 7 (IGFBP7), both related to G1 cell cycle arrest. OBJECTIVES: We now validate a clinical test for urinary [TIMP-2]·[IGFBP7] at a high-sensitivity cutoff greater than 0.3 for AKI risk stratification in a diverse population of critically ill patients. METHODS: We conducted a prospective multicenter study of 420 critically ill patients. The primary analysis was the ability of urinary [TIMP-2]·[IGFBP7] to predict moderate to severe AKI within 12 hours. AKI was adjudicated by a committee of three independent expert nephrologists who were masked to the results of the test. MEASUREMENTS AND MAIN RESULTS: Urinary TIMP-2 and IGFBP7 were measured using a clinical immunoassay platform. The primary endpoint was reached in 17% of patients. For a single urinary [TIMP-2]·[IGFBP7] test, sensitivity at the prespecified high-sensitivity cutoff of 0.3 (ng/ml)(2)/1,000 was 92% (95% confidence interval [CI], 85-98%) with a negative likelihood ratio of 0.18 (95% CI, 0.06-0.33). Critically ill patients with urinary [TIMP-2]·[IGFBP7] greater than 0.3 had seven times the risk for AKI (95% CI, 4-22) compared with critically ill patients with a test result below 0.3. In a multivariate model including clinical information, urinary [TIMP-2]·[IGFBP7] remained statistically significant and a strong predictor of AKI (area under the curve, 0.70, 95% CI, 0.63-0.76 for clinical variables alone, vs. area under the curve, 0.86, 95% CI, 0.80-0.90 for clinical variables plus [TIMP-2]·[IGFBP7]). CONCLUSIONS: Urinary [TIMP-2]·[IGFBP7] greater than 0.3 (ng/ml)(2)/1,000 identifies patients at risk for imminent AKI. Clinical trial registered with www.clinicaltrials.gov (NCT 01573962).

Metabolic acidosis and progression of chronic kidney disease: incidence, pathogenesis, and therapeutic options

In the chronic kidney disease population metabolic acidosis is prevalent presenting already in the early stages of renal dysfunction. The pathogenesis associates the lack of bicarbonate production with the accumulation of organic/inorganic acids and the development of tubulointerstitial damage through ammonium retention and complement deposition. The empiric use of oral sodium bicarbonate represents an interesting therapeutic option that has been documented in a few clinical trials in human subjects. The availability of oral sodium, in its diverse forms, represents an inexpensive and simple way of treating an entity that could hasten the progression of kidney disease, as well as protein catabolism, bone disease and mortality (AU)

Hay una prevalencia importante de la acidosis metabólica en los pacientes que padecen enfermedad renal crónica, presentándose en niveles tempranos de pérdida de filtrado glomerular. La patogénesis se basa en la falta de síntesis de bicarbonato sérico con la acumulación de ácidos de naturaleza orgánica e inorgánica, ocasionando daño tubulointersticial a través de la retención de amoniaco y el depósito de complemento, aunque esta última hipótesis se ha cuestionado en el pasado. El uso empírico de bicarbonato oral representa una opción terapéutica interesante que ha sido utilizada en estudios clínicos recientes. La disponibilidad de bicarbonato de sodio oral en sus diversas formas representa una opción barata y simple de utilizar para decelerar la progresión de la enfermedad renal, sin mencionar las mejoras en el catabolismo proteico, la osteodistrofia renal y la mortalidad (AU)