Primeras recomendaciones de consenso SLANH - COLABIOCLI / Primeiras Recomendações de Consenso SLANH - COLABIOCLI / (Sociedad Latinoamericana de Nefrología e Hipertensión - Confederación Latinoamericana de Bioquímica Clínica) / Informe de la tasa de filtración glomerular estimada junto a la determinación de la creatininemia en población adulta / First SLANH-COLABIOCLI Consensus Recommendations

Resumen La enfermedad renal crónica (ERC) es de alta prevalencia en América Latina y en todo el mundo. Se estima que entre 10 y 20% de la población adulta es portadora de ERC y su prevalencia va en aumento. La ERC progresa en forma silenciosa. Su diagnóstico temprano y oportuno permite iniciar un tratamiento efectivo, en la mayoría de los casos, para detener la enfermedad. Desde hace mucho tiempo, el análisis de la creatininemia es la principal prueba utilizada para valorar la función renal, pero su confiabilidad es limitada. De acuerdo con las recomendaciones de las GUIAS KDOQI del año 2002 la tasa de filtración glomerular estimada (TFGe) obtenida a través de fórmulas, se estableció como una de las herramientas principales para detectar la enfermedad renal de manera precoz, ya que alerta de forma precisa al médico y al equipo de salud sobre el nivel de función renal del paciente. La detección de una TFGe disminuida (menor de 60 mL/min/1,73 m2) es clínicamente relevante, ya que permite establecer el diagnóstico de enfermedad renal en adultos. En el año 2022, en una encuesta realizada por SLANH y COLABIOCLI dirigida a los laboratorios de análisis clínicos de América Latina (n: 237), el 49% de los mismos no informaban la TFGe rutinariamente. En base a esta realidad SLANH y COLABIOCLI elaboraron estas recomendaciones de consenso en referencia al uso de la TFGe.

Abstract Chronic kidney disease (CKD) has a high prevalence worldwide and in Latin America (10 to 20% of the adult population) and is increasing. CKD progresses silently. Opportune diagnosis and treatment are effective in most cases to improve outcomes. Serum creatinine was the main test to assess kidney function, but its reliability is limited. Through the KDOQI Guidelines 2002, the estimated glomerular filtration rate (eGFR) obtained from equations was established as one of the main tools for the early detection of kidney disease in clinical practice. The detection of a decreased eGFR (less than 60 mL/min/1.73 m2) is clinically relevant. This cut-off level establishes the diagnosis of kidney disease in adults. In 2022 SLANH and COLABIOCLI conducted a survey among the clinical laboratories from Latin America. The survey included 237 laboratories, 49% of which did not routinely report the eGFR. Based on this situation, SLANH and COLABIOCLI have elaborated the following consensus recommendations regarding the use of eGFR.

Resumo A doença renal crônica (DRC) é altamente prevalente na América Latina e em todo o mundo. Estima-se que entre 10 e 20% da população adulta seja portadora de DRC e sua prevalência esteja aumentando. A DRC progride silenciosamente. Seu diagnóstico precoce e oportuno permite iniciar um tratamento eficaz, na maioria dos casos, para estancar a doença. Faz muito tempo, a análise da creatinina tem sido o principal teste usado para avaliar a função renal mas sua confiabilidade é limitada. De acordo com as recomendações dos GUIAS KDOQI do ano de 2002, a estimativa da taxa de filtração glomerular (eGFR), obtida por meio de fórmulas, consolidou-se como uma das principais ferramentas para a detecção precoce da doença renal, visto que alerta com precisão ao médico e ao equipe de saúde sobre o nível de função renal do paciente. A detecção de uma eGFR diminuída (inferior a 60 mL/min/1,73 m2) é clinicamente relevante, pois permite estabelecer o diagnóstico de doença renal em adultos. No ano de 2022, em pesquisa realizada pela SLANH e COLABIOCLI dirigida a laboratórios de análises clínicas da América Latina (n: 237), 49% deles não relataram rotineiramente eGFR. Com base nessa realidade, SLANH e COLABIOCLI prepararam essas recomendações de consenso sobre o uso de eGFR.

An Assessment of the Accuracy of Creatinine Measurements in Guyana

ABSTRACT Background: The incidence of chronic kidney disease (CKD) is relatively high in Guyana. Estimated glomerular filtration rate (eGFR) reporting allows for early-stage CKD identification when therapeutic interventions can prevent CKD progression. Accurate creatinine measurements are essential for valid eGFR calculations. Objective: This study was undertaken to assess the accuracy of creatinine measurements in Guyana prior to implementing routine eGFR reporting. Methods: Sixteen Guyanese laboratories participated in this study. Each laboratory received a common set of blinded human serum samples (n = 3) containing clinically relevant creatinine concentrations, assigned by an international reference method (ID-GCMS). Laboratories performed repeated measurements of creatinine in each sample. These data were used to calculate bias, precision and total error (TE) for each creatinine method. Linear regression was used to compare measured creatinine results to assigned reference sample values and to post-analytically correct calibration bias, a priori, for recent patient results from each laboratory. Patient eGFR profiles were compared before and after bias correction. Results: The mean across samples CV and bias for all labs were 9% (range 2.5%-39.3%) and 11% positive (range 0.4%-29.1%), respectively. The mean TE was 28.6%. If the mean TE from a subset of the better performing laboratories (CV < 7%) was to apply nationally, an 'all stage' eGFR misclassification rate of 36% would result. Conclusion: There is a pressing need to improve the accuracy of creatinine measurements in Guyana as, at this time, routine reporting of eGFR by Guyanese laboratories cannot be recommended based on the accuracy data presented in this study.

Comparación de fórmulas para la estimación del filtrado glomerular: correlación e implicancia clínica / Comparison of formulas for the estimation of glomerular filtration: correlation and clinical implication / Comparação de fórmulas para a estimativa da filtração glomerular: correlação e implicações clínicas

La Enfermedad Renal Crónica (ERC) es un importante problema de salud pública que trae aparejada una gran morbi-mortalidad. Una de las herramientas diagnósticas es la estimación del filtrado glomerular (eFG). Los objetivos de este estudio fueron comparar el eFG según dos ecuaciones: MDRD-4 y CKD-EPI, evaluar su comportamiento en valores clínicamente relevantes y evidenciar Enfermedad Renal Oculta (ERO) según cada una de las fórmulas evaluadas, clasificando a la población estudiada en estadíos de ERC. Se evaluaron 2.526 pacientes con factores de riesgo asociados a ERC. La media de los resultados obtenidos con ambas fórmulas fue: para MDRD-4 84,5 mL/min/1,73 m², y para CKD-EPI 90,9 mL/min/1,73 m². De la relación entre el eFG en sus diversos estadíos y los resultados de creatininemia resultó que 83 pacientes se clasificaron como ERO según MDRD-4, y 23 lo hicieron para CDK-EPI, con lo que se manifestó una subestimación de la eFG utilizando la ecuación MDRD-4. La importancia de este estudio radica en el hallazgo precoz y en la prevención de complicaciones que podrían limitar el bienestar de estos pacientes. La participación de Laboratorios nucleados en red brinda herramientas accesibles y de bajo costo para su asistencia temprana, en busca de seguridad, cuidado y educación del paciente.

Chronic Kidney disease (CKD) is an important public health problem which is associated to an increase in mortality. An important diagnostic tool is the estimated glomerular filtration rate (GFR). The aims of this study were to compare GFR according to two different formulas: MDRD-4 and CKD-EPI, in order to evaluate its performance in clinically relevant values and to display occult chronic kidney disease (OCKD) according to each of the equations reviewed to classify the studied population into different stages of CKD. A total of 2526 patients with CKD-associated risk factors were analyzed. Mean of the results with both formulas were: 84.5 mL/min/1.73 m² for MDRD-4 and 90.9 mL/min/1.73 m² for CKD-EPI. Considering the associations between GFR in each of the stages and the results of blood creatinine, 83 patients were classified as OCKD by MDRD-4 while 23 were classified by MDRD-EPI; showing an underestimation of the GFR when using MDRD-EPI. The importance of this study lies in the early detection of the disease and in preventing the complications that could restrict the patient's well-being. The support of the networking laboratories brings the appropriate and low cost tools for an early assistance in search of security, care and education forthe patient.

A Doença Renal Crônica (DRC) é um importante problema de saúde pública que traz grande morbimortalidade. Uma das ferramentas de diagnóstico é a estimativa de filtração glomerular (eFG). Os objetivos deste estudo foram comparar eFG de acordo com duas equações: MDRD-4 e CKD-EPI, avaliar seu comportamento em valores clinicamente relevantes e evidenciar Doença Renal Oculta (DRO) de acordo com cada uma das fórmulas avaliadas, classificando a população estudada em estágios de DRC. Foram avaliados 2526 pacientes com fatores de risco associados à DRC. A média dos resultados obtidos com as duas formulações foi: MDRD-4 a 84,5 mL/min /1,73 m², e CKD-EPI 90,9 mL/min/1.73 m². A relação entre o eFG nas suas diversas fases e os resultados de creatininemia mostrou que 83 pacientes foram classificados como ERO segundo MDRD-4, e 23 fizeram para CDK-EPI, demonstrando uma subestimação da eFG usando a equação MDRD-EPI. A importância desse estudo está na detecção precoce e prevenção de complicações que poderiam limitar o bem-estar desses pacientes. A participação de Laboratórios reunidos em uma rede fornece ferramentas acessíveis e de baixo custo para sua assistência precoce, em busca de segurança, cuidado e educação do paciente.

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.

Relationship between Early Life Factors and Renal Function in Afro-Caribbean Young Adults: Analysis from the Jamaica 1986 Birth Cohort Study / Relación entre los factores de los primeros años de vida y la función renal en adultos jóvenes afrocaribeños: análisis del Estudio de Cohorte de Nacimientos de Jamaica en 1986

ABSTRACT Objective: To investigate the relationship between intrauterine growth and renal function among Jamaican young adults. Methods: Data from 744 participants from the Jamaica 1986 Birth Cohort Study were analysed. We evaluated the relationship between infant characteristics (birthweight and gestational age), maternal characteristics at child's birth (age and socio-economic status), and renal function at ages 18-20 years (using estimated glomerular filtration rate (eGFR), calculated using the Schwartz-Lyon equation and urine albumin excretion), or prevalent chronic kidney disease (CKD; defined as eGFR < 60 ml/minute/1.73 m2 or urinary albumin ≥ 30 mg/g creatinine). Associations were examined using multi-level mixed effects regression models. Results: The mean eGFR was 86.3 ml/minute/1.73 m2 among males and 102.4 ml/minute/1.73 m2 among females (p < 0.001). The prevalence of CKD was 8.3% (7.4% males, 9.1% females, p = 0.387). Birthweight was not significantly associated with eGFR in unadjusted models, but after adjustment for potential confounders/mediators (gender, blood pressure, body mass index, maternal occupation and education), individuals born with a low birthweight (< 2.5 kg) had a 5.1% lower eGFR compared to those with a normal birthweight (β = −0.052, p = 0.002). Furthermore, a one standard deviation increase in birthweight was associated with a 2.2% increase in eGFR (β = 0.022, p = 0.044). No statistically significant associations were observed between early life factors and urinary albumin or CKD in adjusted models. Conclusion: There was a high prevalence of CKD in this Afro-Caribbean young population. Lower birthweight was associated with reduced renal function in early adulthood, which may result in an increased risk of CKD later on in adulthood. Early life interventions may also be warranted in addressing the CKD epidemic.

RESUMEN Objetivo: Investigar la relación entre el crecimiento intrauterino y la función renal entre los adultos jóvenes jamaicanos. Métodos: Se analizaron los datos de 744 participantes en el Estudio de Cohorte de Nacimientos de Jamaica en 1986. Se evaluó la relación entre las características infantiles (peso al nacer y edad gestacional), las características maternas a la hora del nacimiento del niño (edad y estado socioeconómico), y la función renal a la edad de 18 a 20 años (utilizando la tasa de filtración glomerular estimada (TFGe), calculada usando la ecuación Schwartz-Lyon y la excreción de albúmina urinaria), o la enfermedad renal crónica prevalente (ERC; definida como TFGe < 60 ml/min/1.73 m2 o albúmina urinaria ≥ 30 mg/g creatinina). Las asociaciones se examinaron mediante modelos multinivel de regresión de efectos mixtos. Resultados: El TFGe fue de 86.3 ml/min/1.73 m2 entre los varones y 102.4 ml/min/1.73 m2 entre las mujeres (p < 0.001). La prevalencia de ERC fue 8.3% (7.4% varones, 9.1% hembras, p = 0.387). El peso al nacer no se asoció significativamente con la TFGe en los modelos no ajustados, pero después de ajustar los factores de confusión/mediación potenciales (género, presión sanguínea, índice de masa corporal, ocupación y educación materna), los individuos con bajo peso al nacer (< 2.5 kg) tenían un TFGe 5.1% más bajo en comparación con aquellos con un peso normal al nacer (β = −0.052, p = 0.002). Además, un aumento de la desviación estándar en el peso al nacer estuvo asociado con un aumento de 2.2% en TFGe (β = 0.022, p = 0.044). No se observaron asociaciones estadísticamente significativas entre los factores de los primeros años de vida y la albúmina urinaria o ERC en los modelos ajustados. Conclusión: Hubo una alta prevalencia de ERC en esta población de jóvenes afrocaribeños.Un peso más bajo al nacer estuvo asociado con una reducción de la función renal en la edad adulta temprana, lo que puede llevar a un mayor riesgo de ERC más tarde en la edad adulta. Las intervenciones en los primeros años de vida también pueden explicarse al abordar la epidemia de ERC.

Evaluation of creatinine-based and cystatin C-based equations for estimation of glomerular filtration rate in type 1 diabetic patients

ABSTRACT Objective Several formulas based in different biomarkers may be used to estimate glomerular filtration rate (GRF). However, all of them have some limitations, and it is very important to evaluate their performances in different groups of patients. Therefore, we compared GFR, as estimated by creatinine-based and cystatin C-based equations, according to albuminuria, in type 1 diabetes (T1DM), in an observational case-control study. Subjects and methods T1DM patients were classified according to albuminuria: normoalbuminuric (n = 63), microalbuminuric (n = 30), macroalbuminuric (n = 32). GFR was calculated using creatinine-based and cystatin C-based (aMDRD, CKD-EPIcr, CKD-EPIcys, MacIsaac, Tan and CKD-EPIcrcys) equations. Spearman Correlation was used to evaluate the correlation of GFR estimated by the formulas with albuminuria. ROC curves were constructed to compare AUCs of GFR estimated by equations, in reference to macroalbuminuria. Sensibility, specificity and accuracy were calculated for a cut-off < 60 mL/min/1.73 m2. Results GFR estimated by creatinine-based and cystatin C-based equations significantly differed among normoalbuminuric, microalbuminuric and macroalbuminuric patients. Spearman correlation and AUCs of GFR estimated by creatinine-based and cystatin C-based formulas were very similar to each other, though cystatin C-based equations presented better correlation with albuminuria and higher AUCs than the creatinine-based ones, and the best accuracy to detect macroalbuminuric patients. Conclusion Although GFR estimated by all creatinine-based and cystatin C-based equations permitted the differentiation between T1DM patients, according to albuminuria, cystatin C-based equations presented best accuracy to detect macroalbuminuria in T1DM patients and should be considered in the clinical routine in order to increase the possibility of early diagnostic of chronic renal disease.

Enfermedad renal crónica en la población general: importancia de la tasa de filtrado glomerular estimada absoluta / Chronic renal disease in the general population: importance of the absolute estimated glomerular filtration rate

Introducción: Evaluamos la Prevalencia de la Enfermedad Renal Crónica (ERC) en la población general y la asociación con factores de riesgo reconocidos. Determinamos la utilidad de la Tasa de Filtrado glomerular estimada absoluta(TFGea). Métodos: Utilizamos la fórmula MDRD-4 variables corregida por la superficie corporal del individuo evaluado. Se definió como “Probable ERC sin considerar la proteinuria” a la población con TFGea < 60 ml/m y “Probable ERC considerando proteinuria” a la anterior más la población con TFGea ≥ 60 ml/m que presenta proteinuria ≥ 30 mg/L. Regresión logística uni y multivariable para determinar asociación de TFGea < de 60 ml/m con factores comórbidos. Resultados: Se evaluaron 811 personas de edad promedio 52.5 ± 17.0 años. La Tasa de Probable ERC sin considerar a la proteinuria patológica es de 11.7% (IC95%:9.5-14.3) y de 15.8%(IC95%:13.2-18.8) considerándola. El grupo 3a(TFGea 45-59 ml/m) resultó el más frecuente: 9.9 % (IC95%:7.8-12.3). Los factores predictores significativosde TFGea <60 ml/m en el modelo multivariado son: la Mayor edad, la Litiasis Urinaria actual o pasada, el Sexo femenino y el Antecedente de Neoplasia. La TFGe relativa (ml/m/1.73m2) demostró una Tasa de Probable ERC sin considerar proteinuria de 12.8% (IC95%: 10.48-15.54), 1.1% más que la demostrada por la TFGea. Conclusiones: La Prevalencia de Probable ERC es alta en Santa Fe. La mayor edad, la Litiasis Urinaria actual o pasada, el Sexo femenino y el Antecedente de Neoplasia se asocian a TFGea < 60 ml/m. La TFGea permite reducir la Tasa de Probable ERC en el 1.1%.

Introduction: We assessed the prevalence of the Chronic Renal Disease (CRD) in the general population and the association with known risk factors. We determined the use of the absolute estimated glomerular filtration rate ( absolute eGFR) Methods: We used the MDRD formula with 4 variables corrected for body surface area of the examined individual. The population with absolute eGFR < 60 mL/min was defined as “Likely CRD regardless proteinuria” and the latter plus the population with absolute eGFR ≥ 60 mL/ min presenting proteinuria ≥ 30 mg/L was defined as “Likely CRD considering proteinuria”. Univariate and multivariate logistic regression to determine the association between absolute eGFR <60 mL/min with comorbid factors. Results: 811 individuals of an average age of 52.5 ± 17.0 years were examined. The rate of likely CRD without consideration of pathological proteinuria is 11.7% (95% CI:9.5 -14.3) while the rate considering this factor is 15.8% (95% CI:13.2 -18.8). The 3a group (absolute eGFR 45-59 mL/min) was the most frequent one: 9.9 % (95% CI:7.8 -12.3). The significant predictive factors for absolute eGFR <60 mL/min in the multivariate model are: older age, past or current urinary lithiasis, female gender and history of neoplasia. The relative eGFR (mL/min/1.73m2) showed a likely CRD rate without consideration of proteinuria of 12.8% (95% CI: 10.48 -15.54), 1.1% higher than observed for absolute eGFR. Conclusions: The prevalence of potential CRD is high in Santa Fe. The older age, either past or current urinary lithiasis, female gender and history of neoplasia are associated with absolute eGFR < 60 mL/min. Absolute eGFR helps to reduce the rate of likely CRD in 1.1%.

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.

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.

Proposta de padronização de um programa de rastreamento da doença renal crônica / Suggestion of standardization of a screening program for chronic kidney disease

Até recentemente, a prevalência da doença renal crônica (DRC) foi amplamente subestimada. A partir do final do século passado, estudos populacionaisnos Estados Unidos da América, Europa e Oceania revelaram que a prevalência da DRC é mais elevada do que se pensava anteriormente. Tragicamente,a maior parte destes pacientes morre de causas cardiovasculares antes de atingirem o estágio de falência funcional renal. Os dados existentes no Brasilsobre DRC são eminentemente baseados em levantamentos realizados em unidades de diálise. Nossas campanhas de prevenção ainda são realizadas àcusta de esforços individuais, com pouco ou nenhum apoio do poder público, de modo que, embora por vezes atinjam grande número de pessoas, aindageram pouca informação sobre DRC em nosso meio. Neste artigo, os autores apresentam uma proposta de abordagem simples para a identificaçãoprecoce da DRC. Propõem dois fluxogramas de rastreamento das doenças renais, um baseado na proteinúria e outro baseado inicialmente na estimativada filtração glomerular a partir da creatinina e, nas etapas seguintes, orientado pela proteinúria. Chamam a atenção para a necessidade de se gerarinformações mais confiáveis sobre a doença através da uniformização das coletas de dados, assim atraindo a atenção de outros especialistas,particularmente os clínicos gerais, cardiologistas e endocrinologistas, para com isso engajá-los no manejo da DRC.

Until recently, the prevalence of chronic kidney disease (CKD) was widely neglected. However, community based studies done in United States of Ameri -ca, Europe, and Oceania at the end of the last century showed that CKD was more previsously thought. Tragically, most patients with CKD die before theyreach end stage renal failure. So far, in Brazil, the data about CKD, relies mainly on surveys made in dialysis units. Our prevention campaigns are donebased on individual endeavors, generally with little or no support from the public power. As a consequence, a large number of people are screened, although little is still known about the prevalence of CKD. In this review paper, the authors present a proposal to approach, in a simple way, the identification of CKD.It is presented two diagrams to screen for renal diseases, one based on proteinuria and the other starting from glomerular filtration rate estimated from serum creatinine, and then by proteinuria. Although the eventual limitations that any screening program for CKD might have, it is imperative that we standardize the tests for the obtainment of more reliable data, and, thus, to attract more attention for the disease among the other specialists, in order to engage them in the management of the disease.