Metabolic and volume status evaluation of hemodialysis patients with and without residual renal function in the long interdialytic interval / Avaliação metabólica e volêmica no maior intervalo interdialítico de pacientes em hemodiálise com e sem função renal residual

Abstract Introduction: It is unclear whether residual renal function (RRF) in dialysis patients can attenuate the metabolic impact of the long 68-hour interdialytic interval, in which water, acid, and electrolyte accumulation occurs. Objective: to evaluate serum electrolyte levels, water balance, and acid-base status in dialytic patients with and without RRF over the long interdialytic interval (LII). Methodology: this was a single-center, cross-sectional, and analytical study that compared patients with and without RRF, defined by diuresis above 200 mL in 24 hours. Patients were weighed and serum samples were collected for biochemical and gasometric analysis at the beginning and at the end of the LII. Results: 27 and 24 patients with and without RRF were evaluated, respectively. Patients without RRF had a higher increase in serum potassium during the LII (2.67 x 1.14 mEq/L, p < 0.001), reaching higher values at the end of the study (6.8 x 5.72 mEq/L, p < 0.001) and lower pH value at the beginning of the interval (7.40 x 7.43, p = 0.018). More patients with serum bicarbonate < 18 mEq/L (50 x 14.8%, p = 0.007) and mixed acid-base disorder (57.7 x 29.2%, p = 0.042), as well as greater interdialytic weight gain (14.67 x 8.87 mL/kg/h, p < 0.001) and lower natremia (137 x 139 mEq/L, p = 0.02) at the end of the interval. Calcemia and phosphatemia were not different between the groups. Conclusion: Patients with RRF had better control of serum potassium, sodium, acid-base status, and volemia throughout the LII.

Resumo Introdução: Não se sabe ao certo se a função renal residual (FRR) de pacientes dialíticos pode atenuar o impacto metabólico do maior intervalo interdialítico (MII) de 68 horas, no qual ocorre acúmulo de volume, ácidos e eletrólitos. Objetivo: Avaliar os níveis séricos de eletrólitos, balanço hídrico e status ácido-básico de pacientes dialíticos com e sem FRR ao longo do MII. Metodologia: Tratou-se de estudo unicêntrico, transversal e analítico, que comparou pacientes com e sem FRR, definida como diurese acima de 200 mL em 24 horas. Para tal, os pacientes foram pesados e submetidos à coleta de amostras séricas para análise bioquímica e gasométrica no início e fim do MII. Resultados: Foram avaliados 27 e 24 pacientes com e sem FRR, respectivamente. Pacientes sem FRR apresentaram maior aumento de potássio sérico durante o MII (2,67 x 1,14 mEq/L, p < 0,001) atingindo valores mais elevados no fim (6,8 x 5,72 mEq/L, p < 0,001); menor valor de pH no início do intervalo (7,40 x 7,43, p = 0,018), maior proporção de pacientes com bicarbonato sérico < 18 mEq/L (50 x 14,8 %, p = 0,007) e distúrbio ácido-básico misto (70,8 x 42,3 %, p = 0,042), além de maior ganho de peso interdialítico (14,67 x 8,87 mL/kg/h, p < 0,001) e menor natremia (137 x 139 mEq/L, p = 0,02) no fim do intervalo. A calcemia e fosfatemia não foram diferentes entre os grupos. Conclusão: Pacientes com FRR apresentaram melhor controle dos níveis séricos de potássio, sódio, status ácido-básico e da volemia ao longo do MII.

Metabolic and volume status evaluation of hemodialysis patients with and without residual renal function in the long interdialytic interval.

INTRODUCTION: It is unclear whether residual renal function (RRF) in dialysis patients can attenuate the metabolic impact of the long 68-hour interdialytic interval, in which water, acid, and electrolyte accumulation occurs. OBJECTIVE: to evaluate serum electrolyte levels, water balance, and acid-base status in dialytic patients with and without RRF over the long interdialytic interval (LII). METHODOLOGY: this was a single-center, cross-sectional, and analytical study that compared patients with and without RRF, defined by diuresis above 200 mL in 24 hours. Patients were weighed and serum samples were collected for biochemical and gasometric analysis at the beginning and at the end of the LII. RESULTS: 27 and 24 patients with and without RRF were evaluated, respectively. Patients without RRF had a higher increase in serum potassium during the LII (2.67 x 1.14 mEq/L, p < 0.001), reaching higher values at the end of the study (6.8 x 5.72 mEq/L, p < 0.001) and lower pH value at the beginning of the interval (7.40 x 7.43, p = 0.018). More patients with serum bicarbonate < 18 mEq/L (50 x 14.8%, p = 0.007) and mixed acid-base disorder (57.7 x 29.2%, p = 0.042), as well as greater interdialytic weight gain (14.67 x 8.87 mL/kg/h, p < 0.001) and lower natremia (137 x 139 mEq/L, p = 0.02) at the end of the interval. Calcemia and phosphatemia were not different between the groups. CONCLUSION: Patients with RRF had better control of serum potassium, sodium, acid-base status, and volemia throughout the LII.

eNOS gene Glu298Asp and 4b/a polymorphisms are associated with renal function parameters in Mexican patients with Fabry disease.

Fabry disease (FD) is an inherited X-linked lysosomal disease that causes renal failure in a high percentage of affected individuals. The eNOS gene encodes for endothelial nitric oxide synthase, which plays an important role in glomerular hemodynamics. This gene has two main polymorphisms (Glu298Asp and 4b/a) that have been studied in the context of many different diseases, including those involving cardiovascular and renal alterations. Considering the lack of information regarding eNOS variants and FD, we investigated whether there were associations between eNOS genetic variants and renal function parameters in Mexican patients with FD and renal impairment. In total, 15 FD patients with renal alterations were included in the present study, and associations between eNOS polymorphisms and renal function parameters (urea, creatinine, and GFR) were evaluated. The Asp298 and 4a alleles of the eNOS gene were found to be significantly associated with increased levels of urea and creatinine, and a decreased glomerular filtration rate in FD patients, and this association behaved in a co-dominant fashion. Our results coincide with previous reports showing an association between these polymorphisms and kidney disease, and along with other studies regarding their role in the nitric oxide pathway, suggest that these variants affect the severity of nephropathy in patients with FD.

[Protein supplement consumption and its possible association with kidney damage in Mexican elite athletes]. / Consumo de suplemento proteico y su posible asociación con daño renal en atletas mexicanos de alto rendimiento.

BACKGROUND: Protein supplements are one of the most used ergogenic supplements by elite athletes. Nonetheless, it has been postulated that the use of these type of supplements may cause chronic renal failure. The objective of this study is to analyze the effects of the consumption of protein supplements in the renal function of elite athletes of the Mexican Olympic Training Center. METHODS: 74 athletes provided urine samples in order to quantify urinary proteins. Some of them were excluded since they had conditions that could cause proteinuria or alter the quality of the samples. Those that were not excluded were divided into two groups: the experimental group, which included those individuals that had the antecedent of consuming protein supplements, and the control group, that encompassed those individuals that did not had the antecedent of consuming protein supplements. RESULTS: Of the 74 analyzed athletes, 44 were excluded, 11 individuals were included in the experimental group, and 19 in the control group. Microproteinuria was encountered in only one urine sample (control group), and it was determined that there was no significant differences between both groups. CONCLUSION: From the gathered results it can be concluded that protein supplements do not affect renal function. Nonetheless, in the future protein supplements should be evaluated in groups with pathologies or conditions that may compromise renal function.

Introducción: los suplementos proteicos son unos de los suplementos ergogénicos más utilizados por los atletas de alto rendimiento. Sin embargo, se ha postulado que el consumo de estos pudiese ser causa de insuficiencia renal crónica. El objetivo fue analizar los efectos del consumo de suplementos proteínicos en la función renal de los atletas de alto rendimiento del Centro Deportivo Olímpico Mexicano. Métodos: se evaluaron 74 atletas, en cuya muestra de orina se cuantificaron las proteínas. Se excluyeron los atletas con antecedentes o condiciones que pudiesen causar proteinuria o que pudieran alterar la calidad de la muestra. Los elegidos se dividieron en dos grupos con base en el antecedente de consumo de suplemento proteico: el grupo experimental lo conformaron los consumidores y el control los no consumidores. Resultados: de 74 atletas analizados, 44 fueron excluidos, 11 se incluyeron al grupo experimental y 19 al grupo control. Se obtuvo un resultado positivo para microproteinuria en este último grupo. Se determinó estadísticamente que ambos grupos eran similares y se estableció, en relación con el resultado positivo de microproteinura, que no existe una diferencia significativa entre ambos grupos. Conclusión: el consumo de suplemento proteico no ha afectado la función renal de los atletas analizados. Pese a esto, consideramos que la seguridad del suplemento proteico debe ser evaluada en un futuro en ciertos grupos con patologías o antecedentes que pudieran comprometer la función renal.

Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D.

INTRODUCTION: Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting. OBJECTIVE: The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients. PATIENTS AND METHODS: We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation. Estimated glomerular filtration rate (eGFR) was estimated by serum cystatin C and creatinine. In addition, urinary electrolytes and tubular biomarkers (cystatin C, ß2-microglobulin and neutrophil gelatinase-associated lipocalin) were analyzed, as well as parathyroid hormone (PTH) and 25(OH)vitamin D levels. RESULTS: After 1 year, 32 patients completed the study, 22 (68.7%) men and 12 (37.5%) Whites, mean age 44.1±12.0 years. We found that serum electrolytes were similar at baseline and 3 or 12 months after initiation of TDF monotherapy. In addition, urinary fractional excretions of electrolytes as well as proteinuria, albuminuria, urinary ß2-microglobulin, and urinary cystatin C showed no significant differences across the treatment timeline. There were also no statistical differences in the eGFR. There was a statistically significant increase in the PTH (Friedman's test, P=0.012), but the 25(OH)vitamin D levels were in the normal range in the beginning and did not change at the follow-up. Moreover, there was no correlation between the initial levels of vitamin D and the corresponding increases in the PTH values. CONCLUSION: If used as monotherapy in hepatitis B patients for a 12-month period, TDF is not associated with changes in either eGFR or a panel of urinary biomarkers. Serum and urinary electrolytes also remained unchanged. Of note, a significant increase in the PTH was found, although not related to the 25(OH)vitamin D initial status.

Urinary NO3 excretion and renal failure in indinavir-treated patients.

Treatment with indinavir (IDV), a protease inhibitor, is frequently associated with renal abnormalities. We determined the incidence of renal failure (creatinine clearance <80 mL min-1 1.73 (m(2))-1) in HIV patients treated with highly active antiretroviral therapy, including IDV, and investigated the possible mechanisms and risk factors of IDV nephrotoxicity. Thirty-six patients receiving IDV were followed for 3 years. All were assessed for age, body weight, duration of infection, duration of IDV treatment, sulfur-derivative use, total cholesterol, triglycerides, magnesium, sodium, potassium, creatinine, and urinalysis. We also determined renal function in terms of creatinine clearance, urine osmolality and fractional excretion of sodium, potassium, and water. Urinary nitrate (NO3) excretion was measured in 18 IDV-treated patients and compared with that of 8 patients treated with efavirenz, a drug without renal side effects. Sterile leukocyturia occurred in 80.5% of the IDV-treated patients. Creatinine clearance <80 mL min-1 1.73 (m(2))-1 was observed in 22 patients (61%) and was associated with low body weight and the use of sulfur-derivatives. These patients also had lower osmolality, lower urine volume and a higher fractional excretion of water compared to the normal renal function group. Urinary NO3 excretion was significantly lower in IDV-treated patients (809 +/- 181 microM NO3-/mg creatinine) than in efavirenz-treated patients (2247 +/- 648 microM NO3-/mg creatinine, P < 0.01). The lower NO3 excretion suggests that IDV decreases nitric oxide production.

Screening for CLCN5 mutation in renal calcium stone formers patients.

UNLABELLED: Thirty-five patients (23 males and 12 females), age 35 +/- 13 years old, presenting either idiopathic calcium nephrolithiasis, nephrocalcinosis or mild renal failure with idiopathic calcium nephrolithiasis were selected for the analysis of low molecular weight proteinuria and the possible mutations occurrence in the chloride channel gene CLCN5. The urinary ratio of beta2-microglobulin and creatinine (beta2M/Cr) was very high in a transplanted woman with nephrocalcinosis (> 3.23 mg/mmol) and slightly high in five patients (> 0.052 or < 1.0 mg/mmol) with multiple urological manipulations. Other studied patients showed beta2M/Cr ratio at normal range (0.003-0.052 mg/mmol) without gender difference (p > 0.05). Mutation analysis of CLCN5 gene was performed in 26 patients of 35 selected (11 with idiopathic hypercalciuria; 6 men with normal calciuria; 3 with mild renal insufficiency and 6 with nephrocalcinosis) and was normal in all subjects even in those with abnormal molecular weight proteinuria. CONCLUSION: CLCN5 gene mutation is not a common cause of kidney stone disease or nephrocalcinosis in a group of Brazilian patients studied.

Is morning urinary protein/creatinine ratio a reliable estimator of 24-hour proteinuria in patients with glomerulonephritis and different levels of renal function?

BACKGROUND: This cross-sectional study was conducted to determine whether a spot urine protein/creatinine ratio (UPr/UCr) provides accurate quantitation of 24-hr urinary protein excretion (24-hr Prot) in out-patients with primary glomerulonephritis (GN) and different renal function levels. METHODS: Patients were classified into three groups according to creatinine (Cr) clearance (ml/min) and into five categories according to morning UPr/UCr. Correlation between 24-hr Prot and UPr/UCr was calculated according to the three renal function levels. The Bland and Altman method was used to assess agreement between 24-hr Prot and UPr/UCr. Agreement limits were obtained calculating the mean difference between 24-hr Prot and morning UPr/UCr +/- 2SD. Sensitivity and specificity were determined for different renal function levels and UPr/UCr cut-off values. RESULTS: High correlation coefficients (r=0.91, 0.95 and 0.98) were observed in patients with normal, reduced and severely reduced renal function. Differences and variability between 24-hr Prot and UPr/UCr tended to increase with higher proteinuria levels, and this trend was observed for the three renal function levels. The best UPr/UCrcut-off values to detect abnormal or nephrotic proteinuria were, respectively, 0.3 and 2.6. CONCLUSIONS: Correlation and agreement between UPr/UCr and 24-hr Prot was good for all renal function levels, but demonstrated more marked differences as urinary protein excretion increased. Morning UPr/UCr had good sensitivity and specificity for the diagnosis of 24-hr Prot, even in patients with reduced renal function.

Tamm-Horsfall protein excretion to predict the onset of renal insufficiency.

OBJECTIVE: Immunosuppressive therapy after liver transplantation may be a risk for kidney dysfunction. This work was designed to determine whether Tamm-Horsfall Protein (THP) could be considered as a marker for nephrotoxicity. DESIGN AND METHODS: THP was determined by an ELISA method in serial 24-h urine from liver transplant patients. Fourteen patients suffered renal insufficiency (LTr(1)) and 20 showed no acute renal damage (LTr(2)) after liver transplantation. RESULTS: No clear association could be seen between daily THP excretion and plasma creatinine levels by comparing serial samples collected at the same time. Nevertheless, significant differences were observed in pretransplant THP excretion between both groups of patients. The results (Median/Interquartile Range) were: CONTROLS: 113.2/84.9 to 146.8 mg/24 h (n = 30); LTr(1): 36.9/18.3 to 54.5 mg/24 h (p<<0.001 with respect to C and LTr(2)); LTr(2): 90.8/61.5 to 139.7 mg/24 h. CONCLUSIONS: The higher pretransplant synthesis and/or secretion of THP seem to have a protective role on the kidney during and after liver transplantation.

Estimativa da funçäo renal na síndrome de imunodeficiência adquirida - nota prévia / Estimative of the renal function in acquired immunodeficiency syndrome - previous note

Métodos de estimativa da taxa de depuraçao da creatinina (CCr) a partir do nível da creatinina sérica têm sido largamente utilizados. Tais estimadores, contudo têm mostrado precisao variável de acordo com a populaçao estudada. Neste estudo avaliamos o grau de correlaçao e a precisao de três diferentes métodos de estimativa da CCr: as fórmulas de Cockcroft e Gault (CG), de Jellife (J) e o monograma de Sirsbaek-Nielsen (S-N) em um grupo de pacientes com a Síndrome de Imunodeficiência Adquirida (SIDA). Estudamos 43 pacientes (35 homens, 8 mulheres; idade = 37 + 9,1 anos). A média da CCr foi 82 + 43 ml/min. Os coeficientes de correlaçao (r) para (J) foi de 0,62 (IC 95 por cento = 0,39-0,77), enquanto para os outros dois métodos foi de 0,69 (IC 95 por cento = 0,49-0,82). Calculamos o erro de prediçao (EP) e o percentual de erro absoluto de prediçao (PEAP). A média do erro de prediçao tendeu a ser maior com (J) (18 + 38,6) que com (CG) (-3 + 27,5) ou (S-N) (-0,2 + 27,3) nao havendo, entretanto, significância estatística. O mesmo sucedeu ao PEAP que foi respectivamente, de 41 + 47 por cento, 26 + 23 por cento e 27 + 26 por cento. Subdividimos a populaçao em três grupos de acordo com a faixa de CCr: < 80ml/min (n = 15), ( 80 e ( 120 (n = 20) e > 120ml/min (n = 8). Embora as diferenças nao tenham alcançado a significância estatística, houve tendência a um maior PEAP no grupo com CCr < 80ml/min com todos os métodos estudados. Os valores médios de EP indicaram tendência a superestimaçao da CCr neste grupo de pacientes (J = 31,5 + 37; CG = 12,4 + 17; S-N = 17 + 19,5). Estes resultados preliminares sugerem que os métodos de estimativa estudados tendam a causar importante superestimaçao da CCr nos pacientes com SIDA e insuficiência renal, o que pode ocasionar ajustes inadequados na dosagem de drogas excretadas pelo rim, nestes pacientes.