Review on adherence of the literature to official recommendations on albuminuria harmonization and standardization.

Albuminuria standardization is a key issue to produce reliable and equivalent results between laboratories. We investigated whether official recommendations on albuminuria harmonization are followed in the literature. The PubMed database was searched from June 1 to September 26, 2021. The search terms included urine albumin, urine albumin-to-creatinine ratio (uACR), and albuminuria. A total of 159 articles were considered eligible; 50.9 % reported the type of urine collection. Specifically, 58.1 % collected a random spot urine specimen, 21 % collected a first morning void, and 6.2 % collected a 24-h specimen. Overall, 15 % of articles reported data on sample shipping, storage, and centrifugation and 13.3 % mentioned the preanalytical phase without any data on albuminuria. The method for albuminuria was properly described in 31.4 % of articles; of these, 54.9 % used immunological methods, and 8.9 % contained errors or missing data. Most articles (76.7 %) expressed test results as albuminuria-to-creatininuria ratio. Different decision levels were utilized in 130 articles; of these, 36 % used a decision level of ≤30 mg/g creatininuria and 23.7 % used three decision levels (≤30, 30-300, and ≥300 mg/g). The failure to follow guidelines on albuminuria harmonization was mainly found in the preanalytical phase. The poor awareness of the importance of preanalytical steps on test result may be a possible explanation.

[Microalbuminuria in pediatric patients diagnosed with hemolytic uremic syndrome]. / Microalbuminuria en Pacientes Pediátricos Con Diagnóstico de síndrome Hemolítico Urémico.

INTRODUCTION: Hemolytic uremic syndrome (HUS) is characterized by the presence of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. It is the leading cause of acute kidney failure in children under 3 years of age. A variable number of patients develop proteinuria, hypertension, and chronic renal failure. OBJECTIVE: To evaluate the renal involvement in pediatric patients diagnosed with HUS using the microalbumin/creatinine ratio. PATIENTS AND METHODS: Descriptive concurrent cohort study that analyzed the presence of microalbuminuria in patients diagnosed with HUS between January 2001 and March 2012, who evolved without hypertension and normal renal function (clearance greater than 90ml/min using Schwartz formula). Demographic factors (age, sex), clinical presentation at time of diagnosis, use of antibiotics prior to admission, and need for renal replacement therapy were evaluated. RESULTS: Of the 24 patients studied, 54% were male. The mean age at diagnosis was two years. Peritoneal dialysis was required in 45%, and 33% developed persistent microalbuminuria. Antiproteinuric treatment was introduce in 4 patients, with good response. The mean follow-up was 6 years (range 6 months to 11 years). The serum creatinine returned to normal in all patients during follow up. CONCLUSIONS: The percentage of persistent microalbuminuria found in patients with a previous diagnosis of HUS was similar in our group to that described in the literature. Antiproteinuric treatment could delay kidney damage, but further multicenter prospective studies are necessary.

Proteinuria and Electrophoretic Pattern in Dogs with Comorbidities Associated with Chronic Kidney Disease.

In animals with chronic pathologies, the detection of proteinuria via the proteinuria: creatininuria ratio (UPC) and urinary protein electrophoresis allows for the early diagnosis of chronic kidney disease (CKD). The objective of this work was to identify and determine the magnitude of proteinuria and its electrophoretic pattern characterization in dogs with chronic diseases pathophysiologically related to proteinuria. With the studied patients, five groups were formed. The control group (CG) contained non-proteinuric cases. The cases with proteinuria were classified into four groups according to the concurrent disease: chronic inflammatory diseases (IG), neoplasms (NG), heart diseases (HG), and endocrine diseases (EG). For the statistical analysis, descriptive statistics and non-parametric tests were used. Data from 264 dogs were obtained; in the disease groups, proteinuria was observed in more than 30% as the only finding of kidney disease, evidencing a greater risk factor for proteinuria in the HG group (OR 4.047, CI 1.894-8.644, p < 0.0001). In the HG, NG, and EG groups, a higher frequency of glomerular pattern (GEP) related to glomerular hypertension was observed; in the IG, a higher frequency of mixed pattern (MEP) was observed. These findings are secondary to the hyperfiltration process that affects the glomerulus and the renal tubule.

Low Creatininuria due to Hyponatremia Is Reversible in Many Patients.

BACKGROUND: Chronic hyponatremia has been reported to be associated with low solute intake and low creatinine excretion (reflecting likely sarcopenia). We wanted to study the effect, on the long term, of correction of hyponatremia on solute and creatinine excretion in chronic SIADH. METHODS: We made a retrospective review of clinical and biochemical data of patients with euvolemic hyponatremia. We analyzed 24-h urine solute and creatinine excretion in volunteers with hyponatremia induced by dDAVP over 4 days, in 12 patients with chronic SIADH (>1 month) before and after a few days of SNa correction and in 12 patients (6 women and 6 men) before and after 3 months of SNa correction by a vaptan or urea. RESULTS: We confirm a low urine creatinine and solute excretion only in patients with chronic hyponatremia (>1 month). Correction of SNa (from 127 ± 2.3 mEq/L to 139 ± 2.8 mEq/L) for >3 months, in the 12 patients (mean age 58 ± 18), was associated with an increase in 24-h creatinine excretion (from 986 ± 239 to 1,238 ± 220 mg; p < 0.02) and in patients treated with a vaptan (n = 5) solute excretion increased from 656 ± 207 mmol/24 h to 960 ± 193 mmol/24 h (p < 0.02). Sodium excretion increased also in the 12 patients (from 100 ± 53 mEq/24 h to 169 ± 38 mEq/24 h; p < 0.01). CONCLUSION: Chronic hyponatremia (>1 month) is associated with a decrease in solute output (or intake) and in creatinine excretion. In many patients, these abnormalities are reversible in the long term.

Urinalysis and determination of the urine protein-to-creatinine ratio reference interval in healthy cows.

BACKGROUND: There are no reference intervals for urinalysis in cattle. HYPOTHESIS/OBJECTIVES: Characterize the urine of healthy cows, establish urine protein-to-creatinine ratio (UPC) reference intervals, and test possible differences among dairy and beef cattle, age groups, or stage of lactation. ANIMALS: Seventy-seven dairy and 74 beef 2.5 to 17 year-old cows of different breeds housed mainly in free stall. METHODS: In this prospective study, urine specimens were collected by catheterization. Complete urinalysis was performed within 1 hour including specific gravity, dipstick evaluation, visual urine pH evaluation with 0.3 pH unit graded strips, and microscopic evaluation of the sediment. Urinary protein and creatinine concentrations and protein electrophoresis were determined on frozen aliquots. RESULTS: Overall reference intervals were 1.020 to 1.045 for USG, 7.0 to 8.7 for pH, and 0.04 to 0.25 for UPC; because of differences in creatinine concentration, UPC was lower in beef (0.04-0.14) than in dairy (0.05-0.25) cows and in the latter in dry than lactating cows. With dipstick evaluation, most analytes were absent except for blood, ketone, and protein in 24.7, 16.0, and 64.7% of cases, respectively. Microscopic evaluation revealed less than 3 red blood cells, leukocytes, and epithelial cells in 84, 99.3, and 100% cows, respectively. No band was observed at electrophoresis, except in 1 case at MW ~66 000. CONCLUSIONS AND CLINICAL IMPORTANCE: Creatininuria is higher in beef than dairy cows and proteinuria is likely more efficiently characterized by protein concentration than by UPC.

Evolución del paciente quirúrgico grave con ventilación mecánica en cuidados intensivos, según valor de creatininuria / Evolution of critically ill surgical patient with mechanical ventilation in intensive care, according the urine creatinine value

Introducción: El estado nutricional al ingreso influye en la evolución del paciente quirúrgico grave. La creatininuria, indicador de este estado, podría mostrar su posible asociación con la evolución de estos pacientes. Objetivos: Identificar la evolución de los pacientes quirúrgicos graves, con ventilación mecánica invasiva y su posible asociación con la creatininuria al ingreso. Métodos: Se realizó un estudio observacional descriptivo y longitudinal, en 85 pacientes quirúrgicos con ventilación mecánica invasiva, ingresados en la sala de cuidados intensivos, desde enero del 2000 a agosto del 2007. Se evaluó el índice APACHE II al ingreso y la creatininuria en la orina de 24 horas durante 3 días seguidos, con un equipo microprocesador Hitachi 902. El valor medio se contrastó con la mortalidad, morbilidad, estadía en cuidados intensivos y tiempo de ventilación mecánica. Las variables cuantitativas se expresaron como media, con desviación estándar y las cualitativas, como frecuencias absolutas o porcentajes. La comparación de medias se realizó con la t de Student. La asociación entre variables cualitativas se evaluó con ji cuadrado. Resultados: La edad media fue de 52,3 ± 15,8 años; el 54,1 por ciento correspondió al sexo masculino y el índice de APACHE II fue 20,4 ± 6 puntos. El diagnóstico más frecuente fue la peritonitis secundaria (49,4 por ciento). Los valores inferiores de creatininuria se asociaron a la mortalidad, presencia de complicaciones, mayor estadía en cuidados intensivos y del tiempo de ventilación mecánica. Conclusiones: La creatininuria al ingreso está asociada a la evolución de los pacientes quirúrgicos con ventilación mecánica invasiva(AU)

Introduction: The nutritional status at admission influences the evolution of the severely ill surgical patient. Urine creatinine, an indicator of this state, could show its possible association with the evolution of these patients. Objectives: To identify the evolution of critically ill surgical patients with invasive mechanical ventilation and its possible association with urine creatinine on admission. Methods: A descriptive and longitudinal observational study was carried out in 85 surgical patients with invasive mechanical ventilation, admitted to the Intensive Care Unit, from January 2000 to August 2007. The APACHE II index on admission and urine creatinine in the 24-hour urine for 3 consecutive days, with a Hitachi 902 microprocessor equipment. The mean value was contrasted with mortality, morbidity, stay in intensive care and time on mechanical ventilation. Quantitative variables were expressed as mean, with standard deviation, and qualitative variables, as absolute frequencies or percentages. The comparison of means was carried out with Student's t test. The association between qualitative variables was evaluated with chi square. Results: The mean age was 52,3 ± 15,8 years; 54,1 percent corresponded to the male sex and the APACHE II index was 20,4 ± 6 points. The most frequent diagnosis was secondary peritonitis (49,4 percent). Lower urine creatinine values ​​were associated with mortality, the presence of complications, a longer stay in intensive care and the time on mechanical ventilation. Conclusions: Urine creatinine on admission is associated with the evolution of surgical patients with invasive mechanical ventilation(AU)

Correlación entre el cociente proteinuria/creatininuria en una orina al azar y la proteinuria de 24 horas

Introducción: la cuantificación de proteínas en orina es un estudio que evalúa la afectación renal por ciertas enfermedades. Su medición puede realizarse también a través del cociente proteinuria/creatininuria. Objetivo: determinar la correlación entre el cociente proteinuria/creatininuria y la proteinuria de 24 horas. Metodología: se realizó un estudio descriptivo observacional, prospectivo con componente analítico de corte transverso, de muestreo no probabilístico. Se incluyó a 60 pacientes con factores de riesgo de padecer enfermedad renal crónica, que acudieron al Hospital Nacional (Itauguá) en el año 2014. Todos se realizaron análisis de orina de 24 horas y de una muestra de orina al azar para estimar el cociente proteinuria/creatininuria. Resultados: se observó que existe una correlación muy significativa (r= 0,9 p < 0,001) entre los valores del cociente de proteinuria/creatininuria en una orina al azar y la proteinuria de 24 horas, con una sensibilidad 94,1% (IC95% 79-100), especificidad 100% (IC95% 98-100%), valor predictivo positivo 100% (IC95% 96-100) y valor predictivo negativo 97,7% (IC95% 92-100). Conclusiones: el cociente proteinuria/creatininuria es útil para detectar proteinuria en rango no nefrótico.

Introduction: The quantification of proteins in urine is a study that evaluates kidney involvement in some diseases. The measurement can be made through the urine protein-creatinine ratio. Objective: To determine the correlation between the urine protein-creatinine ratio and 24-hour urine protein. Methodology: A cross-sectional prospective observational descriptive study with analytical component and non-probabilistic sampling was performed. Sixty patients who had risk factors of chronic renal disease and attended the National Hospital (Itauguá) in 2014 were included. Twenty four-hour urine and a random urine sample were analyzed to estimate the protein-creatinine ratio. Results: A very significant correlation (r= 0.9 p < 0.001) was observed between the values of the protein-creatinine ratio in a random urine and 24-hour urine protein with a sensitivity of 94.1% (IC95% 79-100), specificity of 100% (IC95% 98-100%), positive predictive value of 100% (IC95% 96-100) and negative predictive value of 97.7% (IC95% 92-100). Conclusion: The protein-creatinine ratio is useful to detect proteinuria in a non-nephrotic range.

Microalbuminuria en pacientes pediátricos con diagnóstico de síndrome hemolítico urémico / Microalbuminuria in pediatric patients diagnosed with hemolytic uremic syndrome

Introducción: El síndrome hemolítico urémico (SHU) se caracteriza por la presencia de anemia hemolítica microangiopática, trombocitopenia y afectación renal aguda. Es la principal causa de falla renal aguda en niños menores de 3 años. Un número variable de pacientes evoluciona con afectación renal a largo plazo con proteinuria, hipertensión arterial e insuficiencia renal crónica. Objetivo: Evaluar la afectación renal mediante el índice microalbuminuria/creatininuria en pacientes pediátricos con diagnóstico de SHU. Pacientes y Método: Estudio descriptivo de cohorte concurrente que analizó la presencia de microalbuminuria en pacientes diagnosticados de SHU entre enero de 2001 y marzo de 2012, que evolucionaron sin hipertensión y con función renal normal (clearance mayor de 90 ml/min medido por fórmula de Schwartz). Se evaluaron factores demográficos (edad, sexo), presentación clínica en el momento del diagnóstico, uso de antibióticos previo al ingreso y requerimiento de terapia de reemplazo renal. Resultados: Se estudiaron 24 pacientes, el 54% varones; la edad promedio en el momento del diagnóstico fue de 2 años; un 45% requirió diálisis peritoneal; un 33% evolucionó con microalbuminuria persistente; cuatro pacientes recibieron tratamiento antiproteinúrico con buena respuesta. El promedio de seguimiento fue de 6 años (rango: 6 meses a 11 años); todos los pacientes durante el seguimiento evolucionaron con creatinina plasmática normal. Conclusiones: En nuestro grupo, el porcentaje de microalbuminuria persistente en pacientes con diagnóstico previo de SHU fue similiar a lo descrito en la literatura; el tratamiento con antiproteinúricos podría retrasar el daño renal, pero es necesario realizar estudios prospectivos multicéntricos.

Introduction: Hemolytic uremic syndrome (HUS) is characterized by the presence of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. It is the leading cause of acute kidney failure in children under 3 years of age. A variable number of patients develop proteinuria, hypertension, and chronic renal failure. Objective: To evaluate the renal involvement in pediatric patients diagnosed with HUS using the microalbumin/creatinine ratio. Patients and Methods: Descriptive concurrent cohort study that analyzed the presence of microalbuminuria in patients diagnosed with HUS between January 2001 and March 2012, who evolved without hypertension and normal renal function (clearance greater than 90 ml/min using Schwartz formula). Demographic factors (age, sex), clinical presentation at time of diagnosis, use of antibiotics prior to admission, and need for renal replacement therapy were evaluated. Results: Of the 24 patients studied, 54% were male. The mean age at diagnosis was two years. Peritoneal dialysis was required in 45%, and 33% developed persistent microalbuminuria. Antiproteinuric treatment was introduce in 4 patients, with good response. The mean follow-up was 6 years (range 6 months to 11 years). The serum creatinine returned to normal in all patients during follow up. Conclusions: The percentage of persistent microalbuminuria found in patients with a previous diagnosis of HUS was similar in our group to that described in the literature. Antiproteinuric treatment could delay kidney damage, but further multicenter prospective studies are necessary.

Primer Consenso Nacional sobre Proteinuria en el diagnóstico y la evaluación de la enfermedad renal crónica en Adultos / First National Consensus on Proteinuria in the diagnosis and evaluation of chronic kidney disease in Adults

Mediante revisión de PubMed y opinión de expertos los autores concluyeron que proteinuria y albuminuria son marcadores de diagnóstico de enfermedad renal crónica (ERC), son indicadores de progresión y por lo tanto un objetivo terapéutico y además son marcadores de riesgo de muerte y enfermedad CV tanto en población general como en pacientes con ERC. Estos resultados se confirmaron utilizando la tira reactiva, el cociente albuminuria/creatininuria (A/C) o el cociente proteinuria/creatininuria (P/C) en muestra de orina con referencia a la proteinuria en orina de 24 hs (gold standard). El índice A/C parece ser el método ideal porque será el más fácil de estandarizar, pero su costo es mayor y el índice P/C es buen predictor a un costo menor. Las tiras reactivas tienen 29% de falsos positivos pero si somos estrictos en la recolección de la muestra de orina y la lectura es automatizada se reduce la posibilidad de error y la variabilidad de resultados. Se establecen por consenso las etapas preanalíticas, analíticas y post-analíticas de la medición de proteinuria y albuminuria en laboratorio para precisar mejor el diagnóstico y evolución de ERC.