Evaluation of the stability of polyamines in human serum at different storage temperatures using capillary electrophoresis with indirect ultraviolet detection.

Polyamines are low molecular weight compounds that are present in all living organisms. They are related to the pathological processes, and have been studied as biomarkers for tumor progression, being analyzed in patients' biological fluids. However, polyamines can undergo degradation in serum samples, depending on storage conditions, which impairs their quantification in these matrices. In this work, capillary electrophoresis using indirect ultraviolet detection has been developed and applied to evaluate the stability of polyamines [cadaverine (Cad), putrescine (Put), spermine (Spm), and spermidine (Spd)] in human serum at different storage temperatures. By using this method, Cad, Put, Spm, and Spd were separated in less than 4 min. The range of the correlation coefficients was 0.993-0.998. The corresponding limits of detection and quantification were as follows (in mg L-1 ): Spm: 0.209 and 0.697; Spd: 0.165 and 0.549; Put: 0.189 and 0.632; Cad: 0.125 and 0.417. Besides, the coefficient of variation was lower than 1% for all analytes and the recovery was 92%-110%. The method was successfully applied for polyamines spiked in human serum samples from healthy people. The results showed that the degradation of polyamines was lower in samples stored in a freezer (-20°C).

Autoantibodies against phospholipase A2 receptor in Brazilian patients with glomerular diseases.

BACKGROUND: Recently, great progress has been made in understanding the pathogenesis of membranous nephropathy (MN) with the discovery of autoantibodies (Abs) to M-type phospholipase A2 receptor (PLA2R) in serum and in immunocomplexes deposited in glomerulus in most adult patients with primary MN. OBJECTIVE: To evaluate the diagnostic performance of anti-PLA2R in Brazilian patients with MN, as well as to verify the possible association of anti-PLA2R serum levels with disease activity. METHODS: 117 patients with glomerular diseases confirmed by renal biopsy underwent routinely clinical and laboratory evaluation (serum creatinine and albumin, 24-h proteinuria, urinalysis, tests for etiological investigation) and determination of serum anti-PLA2R by ELISA. RESULTS: 67.5% of the patients had MN, 9.4% focal segmental glomerulosclerosis, 7.7% lupus nephritis class V and 15.4%, other proteinuric glomerular diseases. The mean level of glomerular filtration rate (estimated by the CKD-EPI formula) was 79.43 mL/min (12.00-151.20 mL/min), 24 h proteinuria of 2.89 g (0-14.90 g), serum albumin of 3.79 g/dL (1.20-4.80 g/dL). Anti-PLA2R was detected in 27 patients, all with active MN, being 26 primary and 1 secondary MN. Sensitivity and specificity rates for the test were 60.5-94.7%, and positive (PPV) and negative (NPV) predictive values were 92.9 and 67.9%, respectively. CONCLUSIONS: Anti-PLA2R showed high specificity and PPV for the diagnosis of primary MN in Brazilian patients. There was a strong correlation between disease activity and positive anti-PLA2R. This biomarker represents an important diagnostic tool for primary MN and may contribute to the monitoring of disease activity in such patients.

Pregnancy in renal transplant patients: Renal function markers and maternal-fetal outcomes.

OBJECTIVES: We aimed to evaluate laboratory markers in women who got pregnant after renal transplantation. STUDY DESIGN: Cross-sectional prospective study. MAIN OUTCOME MEASURES: Renal function parameters and maternal and fetal data were assessed in renal transplant recipients. RESULTS: Forty-three women who got pregnant after renal transplantation (mean age, 28.5 years; mean gestational age, 35.6 weeks) were included. Most patients (53.5%) received a renal transplant from a deceased donor. Podocyturia was not significantly correlated with other renal function markers. Mean period from transplantation to pregnancy was approximately 5 years; this period was not associated with obstetric complications or changes in renal markers. A gradual increase was observed in the following parameters during pregnancy and puerperium: serum creatinine levels (P < 0.001), proteinuria (P < 0.001), urinary protein/creatinine ratio (P < 0.001), and albumin/creatinine ratio (P < 0.001). The sensitivity and specificity of protein/creatinine ratio in predicting preeclampsia were high (96.0% and 94.0%, respectively). Elevated serum creatinine levels, urinary albumin/creatinine ratio, and retinol-binding protein levels in the third trimester were associated with prematurity (P < 0.001). Preeclampsia was the main cause of renal function decline at the end of pregnancy (65.0% of cases). Approximately four (9.5%) pregnant women presented with premature rupture of membranes and 18 (42.0%) with a urinary tract infection. CONCLUSIONS: Proteinuria, urinary protein/creatinine ratio, and retinol-binding protein levels were elevated in patients with preeclampsia. Using these markers to assess renal function during pregnancy may be clinically useful for detecting and monitoring renal injury in renal transplant recipients.

Pregnancy as an early stress test for cardiovascular and kidney disease diagnosis.

OBJECTIVES: Pregnancy is a cardiometabolic and renal stress test for women, primarily when associated with hypertension syndrome, which can have deleterious effects in the long term. We undertook this study to make a long-term evaluation on these women. STUDY DESIGN: A retrospective cohort study was conducted to investigate voluntary women who had pregnancy-induced hypertension syndrome versus normal pregnancy. MAIN OUTCOME MEASURES: We evaluated a total of 85 women, divided in case (n = 25) and control (n = 60) groups, by clinical, anthropometric and epidemiological profiles, general, metabolic and renal tests, and risk stratification for cardiovascular disease (CVD) and chronic kidney disease (CKD). RESULTS: The case group showed a higher incidence of hypertension (P = .003), shorter period between its diagnosis and end of pregnancy (P < .001) and lower age at diagnosis (P = .033); higher weight (P < .001), body mass index (BMI) (P < .001), waist-to-height ratio (p = .001) and abdominal circumference (P < .001); higher fat percentage (P = .004) and weight to lose (P < .001) as measured by bioimpedance; lower estimate glomerular filtration rate (eGFR) by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation (P = .021), greater difference between estimated vascular age and real age (P = .008) according to Framingham Risk Score (2008) and higher frequency of metabolic syndrome (P < .001). CONCLUSIONS: Women who had pregnancy-induced hypertension syndrome were found with a higher incidence of obesity, metabolic syndrome and hypertension, earlier onset of hypertension, higher estimated vascular age and lower eGFR. These findings reinforce the importance of investigating the history of hypertension syndrome in pregnancy, which should be considered an indicator to be followed long term after childbirth.

Urinary abnormalities and renal function in pregnant women with chronic hypertension. / Avaliação de alterações urinárias e função renal em gestantes com hipertensão arterial crônica.

INTRODUCTION: Renal involvement in pregnant women with chronic hypertension is not widely known. OBJECTIVES: 1- To describe the epidemiological profile of pregnant women with chronic hypertension; 2- To evaluate urinary abnormalities (by urinalysis), renal function (serum creatinine and cystatin C, and estimated glomerular filtration rate (eGFR); 3- To evaluate the pregnancy outcome in chronic hypertension. METHODS: 103 pregnant women with chronic hypertension (blood pressure over 140/90 mmHg, detected previously to pregnancy or until the 20th week) were submitted to clinical and laboratorial evaluation. RESULTS: Pregnant women were 21-45 (mean: 34) years-old. Protein/creatinine ratio in random urine was elevated in 5.2% (0.0-6.4g/g), serum creatinine in 19.6% and cystatin C in 14.7% of them. It was observed that characteristics of pregnant patients and their newborns (vs. frequencies of the cases with CKD-EPI cystatin C < 60 ml/min/1.73 m2) were: 20.5% (33.3%) of preterm birth < 37 weeks, 17.5% (22.2%) of birth weight < 2500g and 17.5% (22.2%) of small for gestational age; superimposed preeclampsia-eclampsia occurred in 24.7% (22.2%) of the cases. CONCLUSIONS: Renal abnormalities were detected by proteinuria, determinations of serum creatinine and cystatin C in 5.2, 19.6 and 14.7% of the cases. The results suggest that the formulas CKD-EPI and MDRD can have applicability in assessing renal function in pregnant women. It was also shown a high frequency of preterm birth or with < 2500g at birth or small for gestational age, as well as of superimposed preeclampsia-eclampsia (24.7%) in pregnant women with chronic hypertension.

Avaliação de alterações urinárias e função renal em gestantes com hipertensão arterial crônica / Urinary abnormalities and renal function in pregnant women with chronic hypertension

Resumo Introdução: O acometimento renal em gestantes portadoras de hipertensão arterial crônica (HAC) não é amplamente conhecido. Objetivos: 1- Descrever o perfil epidemiológico de pacientes com HAC; 2- Avaliar a ocorrência de alterações urinárias e de função renal (por meio de determinação sérica de creatinina, cistatina C e ritmo de filtração glomerular estimada - RFGe); 3- Avaliar o desfecho das gestações em HAC. Métodos: Foram submetidas a avaliações clínicas e laboratoriais 103 gestantes com HAC (pressão arterial acima de 140/90 mmHg, identificada previamente à gestação ou até a 20ª semana). Resultados: As gestantes tinham 21-45 (média: 34) anos; 12,6% eram primigestas, 64,1% tiveram múltiplas gestações. A relação proteinúria/creatininúria em amostra isolada estava alterada em 5,2% casos (0-6,44 g/g), creatinina sérica estava elevada em 19,6% e cistatina C em 14,7%. Na avaliação das características da gestação em pacientes com HAC e seus recém-nascidos (RN) (vs. frequências nos casos com CKD-EPI cistatina C < 60 ml/min/1,73 m2), observou-se: 20,5% (33,3%) de nascidos pré-termo < 37 sem, 17,5% (22,2%) de RN com peso < 2500 g e 17,5% (22,2%) de RN pequeno para a idade gestacional (PIG); sobreposição de DHEG ocorreu em 24,7% (22,2%) dos casos. Conclusão: Alterações renais foram identificadas por proteinúria, creatinina e cistatina C séricas em 5,2%, 19,6 e 14,7% das gestantes. Os resultados sugerem que as fórmulas do CKD-EPI e MDRD também podem ter aplicabilidade nessa avaliação em gestantes. Detectou-se alta frequência de RN pré-termo ou com menos de 2500 g ao nascer ou PIG, assim como de sobreposição de DHEG (24,7%) em gestantes com HAC.

Abstract Introduction: Renal involvement in pregnant women with chronic hypertension is not widely known. Objectives: 1- To describe the epidemiological profile of pregnant women with chronic hypertension; 2- To evaluate urinary abnormalities (by urinalysis), renal function (serum creatinine and cystatin C, and estimated glomerular filtration rate (eGFR); 3- To evaluate the pregnancy outcome in chronic hypertension. Methods: 103 pregnant women with chronic hypertension (blood pressure over 140/90 mmHg, detected previously to pregnancy or until the 20th week) were submitted to clinical and laboratorial evaluation. Results: Pregnant women were 21-45 (mean: 34) years-old. Protein/creatinine ratio in random urine was elevated in 5.2% (0.0-6.4g/g), serum creatinine in 19.6% and cystatin C in 14.7% of them. It was observed that characteristics of pregnant patients and their newborns (vs. frequencies of the cases with CKD-EPI cystatin C < 60 ml/min/1.73 m2) were: 20.5% (33.3%) of preterm birth < 37 weeks, 17.5% (22.2%) of birth weight < 2500g and 17.5% (22.2%) of small for gestational age; superimposed preeclampsia-eclampsia occurred in 24.7% (22.2%) of the cases. Conclusions: Renal abnormalities were detected by proteinuria, determinations of serum creatinine and cystatin C in 5.2, 19.6 and 14.7% of the cases. The results suggest that the formulas CKD-EPI and MDRD can have applicability in assessing renal function in pregnant women. It was also shown a high frequency of preterm birth or with < 2500g at birth or small for gestational age, as well as of superimposed preeclampsia-eclampsia (24.7%) in pregnant women with chronic hypertension.

Is there a role for urinary podocyte excretion assessment in lupus nephritis?

OBJECTIVE: To establish the occurrence and intensity of podocyturia and its relation to grade of disease activity, as defined by clinical and laboratory criteria. METHODS: Prospective, cross-sectional study involving 50 patients with lupus nephritis and 29 controls, which had podocyturia levels determined from random urine samples using an immunofluorescence technique. Disease activity was graded by BILAG (renal criteria) and an additional system used in the service (S2). RESULTS: Fifty patients with lupus nephritis (WHO classes III, IV and V), with a median age of 37 years, were evaluated. Of these, 86.5% were female, and 52% were BILAG A. Podocyturia quantification in the lupus nephritis and control groups differed significantly (p = 0.009). This score was higher in relation to classes III, IV and V. The correlation with C3 consumption was stronger (p = 0.011) than with C4. The highest levels were found in the most active groups (A and B of BILAG and S2). Lower podocyturia correlated with a lower dose of prednisone. There was no association with the intensity of proteinuria, hematuria or pyuria, serum creatinine levels, among others. CONCLUSIONS: Podocyturia assessment, which was performed by immunofluorescence in this study, can be used as an indicator of disease activity with the advantage of being a urinary biomarker. The levels proved to be higher in patients with lupus nephritis than in the controls and were particularly higher in class IV.

It is time to review concepts on renal involvement in leprosy: pre- and post-treatment evaluation of 189 patients.

BACKGROUND: Functional and morphological renal lesions have been widely described in leprosy for decades. Nevertheless few studies have assessed renal function pre- and during treatment after the advent of multidrug therapy (MDT). METHODS: This is a prospective study involving 189 consecutive patients, with all forms of leprosy (Ridley-Jopling scale). Laboratory (serum urea and creatinine, estimated GFR, urinalysis, microalbuminuria, urinary RBP) and clinical features of renal disease were evaluated previously and after onset (3 and 8 months later) of MDT. RESULTS: One hundred and eighty-nine patients (M 1.8: F 1; mean age 44 ± 16 years) were included just after diagnosis of leprosy and before the introduction of MDT. Mean time until manifestation of symptoms and/or signs of leprosy was 29 ± 56 months (25 days-480 months). Microhematuria and microalbuminuria were detected in 7.5% and 9.6% of the cases, respectively. Elevated serum creatinine was detected in 34% pre-MDT; this was statistically more frequent in males, hypertensive and frequent users of non-steroidal anti-inflammatory drugs (NSAID), as well as in patients with erythema nodosum lepromatosum, 45.5% by the time of diagnosis, 18% after 3 months and 9% after 8 months of MDT (p = 0.039). CONCLUSIONS: Our results suggest that functional renal lesions in leprosy are currently mild and predominantly of glomerular origin, in opposition to the severe involvement described in the past. This improved outcome of renal disease secondary to leprosy is possibly due to the advent of MDT and effective treatment of episodes of reaction, leading to shorter periods of active infectious disease.

[Podocyturia in pregnant women with chronic hypertension may predict kidney injury?]. / Podocitúria em gestantes hipertensas crônicas pode predizer dano renal?

PURPOSE: To evaluate the presence of podocyturia in chronic hypertensive pregnant women in the third trimester of pregnancy and its possible association with renal disease. METHODS: This was an observational study of a convenience sample of 38 chronic hypertensive pregnant women. The podocytes were labeled by the indirect immunofluorescence technique with anti-podocin and diamidino-phenylindole (DAPI). The count was made on 30 random fields analyzed and corrected according to urinary creatinine (podocytes/mg creatinine). The patients were assigned to two groups: NG (normal glomerular function), up to 100 podocytes, and GP (probable glomerulopathy), more than 100 podocytes. Urinary creatinine was measured by the alkaline picrate method. The variables analyzed were body mass index, gestational age, and systolic and diastolic blood pressure at the time of sample collection. Data were analyzed using the SPSS - version 16.0 (IBM - USA). Statistical analysis was performed by the χ2 test, and significant differences were considered when p<0.05. RESULTS: The median podocyte count was 20.3 (0.0-98.1) for group GN, and 176.9 (109.1-490.6) for GP. The mean body mass index was 30.2 kg/m2 (SD=5.6), mean gestational age was 35.1 weeks (SD=2.5), median systolic blood pressure was 130.0 mmHg (100.0-160.0) and median diastolic blood pressure was 80.0 mmHg (60.0-110.0). There was no significant correlation between podocyturia and body mass index (p=0.305), gestational age (p=0.392), systolic blood pressure (p=0.540) or diastolic blood pressure (p=0.540). CONCLUSIONS: In this study, there was no podocyturia pattern consistent with the presence of active renal disease, although some of the women studied (15.8%) exhibited a significant loss. We believe that it is premature to recommend the inclusion of the determination of podocyturia in routine prenatal clinical practice in chronically hypertensive pregnant women.

Iohexol clearance for determination of glomerular filtration rate in rats induced to acute renal failure.

INTRODUCTION: The glomerular filtration rate (GFR) is considered an especially important tool for the measurement of renal function. Inulin clearance (InCl) is the classic reference method for this purpose, although it is associated with a number of disadvantages; thus, other markers have been proposed, including iohexol. Determination of iohexol clearance (IoCl) has been established for clinical use; however, its application as a GFR marker in experimental rat models has not been reported. OBJECTIVES: This study aims to standardize a methodology for the measurement of iohexol clearance and to evaluate its applicability as a marker of GFR in rats with induced toxic acute renal failure (ARF), using InCl as the gold standard. MATERIALS AND METHODS: Twenty-six Wistar male rats (200-300 g) were divided into the following two groups: a control group (n=7) and an ARF group (n=19). ARF was induced by the subcutaneous administration of cisplatin (5 mg/kg); IoCl and InCl were determined simultaneously, and plasma creatinine (pCreat) dosage was measured colorimetrically. RESULTS: The pCreat, InCl and IoCl levels were consistent with the expected values for the renal function ranges of the evaluated animals, and the IoCl and InCl levels were significantly correlated (r=0.792). An inverse moderate linear correlation between the IoCl and pCreat measurements (r=-0.587) and between the InCl and pCreat measurements (r=-0.722) were observed. CONCLUSION: These results confirm a correlation between IoCl and the gold standard of GFR, InCl measurement. IoCl offers a relevant advantage over InCl because determination of the former allows the animal to live after the procedure.

Podocitúria em gestantes hipertensas crônicas pode predizer dano renal? / Podocyturia in pregnant women with chronic hypertension may predict kidney injury?

OBJETIVO: Avaliar a presença de podocitúria em gestantes hipertensas crônicas no terceiro trimestre da gestação e a associação com doença renal. MÉTODOS: Estudo observacional descritivo em uma amostra de conveniência de 38 gestantes hipertensas crônicas. Os podócitos foram marcados com técnica de imunofluorescência indireta com antipodocina e diamidino-fenilindol (DAPI). A contagem foi feita a partir de 30 campos analisados de forma aleatória, corrigida pela creatinina urinária (podócitos/mg de creatinina). Foram assumidos dois grupos: grupo GN (função glomerular normal), com até 100 podócitos, e grupo GP (provável glomerulopatia), com mais de 100 podócitos. A dosagem de creatinina foi realizada com uso da técnica do picrato alcalino. As variáveis de análise foram o índice de massa corpórea, a idade gestacional na coleta, a pressão arterial sistólica e a pressão arterial diastólica no momento da coleta. Para a análise dos dados, foi utilizado o programa SPSS - versão 16.0. (IBM - USA). Nas análises estatísticas, foi utilizado o teste do χ2, sendo consideradas diferenças significantes valores de p<0,05. RESULTADOS: A contagem de podócitos no grupo GN teve mediana de 20,3 (0,0 a 98,1), e no grupo GP, de 176,9 (109,1 a 490,6). A média do índice de massa corpórea foi 30,2 kg/m2 (DP=5,6), a média da idade gestacional foi de 35,1 semanas (DP=2,5), a mediana da pressão arterial sistólica foi de 130,0 mmHg (100,0-160,0) e a mediana da pressão arterial diastólica de 80,0 mmHg (60,0-110,0). Não houve correlação significativa entre podocitúria e índice de massa corpórea (p=0,305), idade gestacional na coleta (p=0,392), pressão arterial sistólica (p=0,540) e pressão arterial diastólica (p=0,540). CONCLUSÕES: Não foi identificado um padrão de podocitúria compatível com a presença de glomerulopatia ativa, ainda que algumas das gestantes (15,8%) tenham exibido perda podocitária expressiva. Consideramos ser prematuro recomendar para a prática ...

PURPOSE: To evaluate the presence of podocyturia in chronic hypertensive pregnant women in the third trimester of pregnancy and its possible association with renal disease. METHODS: This was an observational study of a convenience sample of 38 chronic hypertensive pregnant women. The podocytes were labeled by the indirect immunofluorescence technique with anti-podocin and diamidino-phenylindole (DAPI). The count was made on 30 random fields analyzed and corrected according to urinary creatinine (podocytes/mg creatinine). The patients were assigned to two groups: NG (normal glomerular function), up to 100 podocytes, and GP (probable glomerulopathy), more than 100 podocytes. Urinary creatinine was measured by the alkaline picrate method. The variables analyzed were body mass index, gestational age, and systolic and diastolic blood pressure at the time of sample collection. Data were analyzed using the SPSS - version 16.0 (IBM - USA). Statistical analysis was performed by the χ2 test, and significant differences were considered when p<0.05. RESULTS: The median podocyte count was 20.3 (0.0-98.1) for group GN, and 176.9 (109.1-490.6) for GP. The mean body mass index was 30.2 kg/m2 (SD=5.6), mean gestational age was 35.1 weeks (SD=2.5), median systolic blood pressure was 130.0 mmHg (100.0-160.0) and median diastolic blood pressure was 80.0 mmHg (60.0-110.0). There was no significant correlation between podocyturia and body mass index (p=0.305), gestational age (p=0.392), systolic blood pressure (p=0.540) or diastolic blood pressure (p=0.540). CONCLUSIONS: In this study, there was no podocyturia pattern consistent with the presence of active renal disease, although some of the women studied (15.8%) exhibited a significant loss. We believe that it is premature to recommend the inclusion of the determination of podocyturia in routine prenatal clinical practice in chronically hypertensive pregnant women. .

Estimation of glomerular filtration rate from serum creatinine and cystatin C in octogenarians and nonagenarians.

BACKGROUND: Equations to estimate GFR have not been well validated in the elderly and may misclassify persons with chronic kidney disease (CKD). We measured GFR and compared the performance of the Modification of Diet in Renal Disease (MDRD), the Chronic Kidney Disease-Epidemiology Collaboration (CKD-Epi) and the Berlin Initiative Study (BIS) equations based on creatinine and/or cystatin C in octogenarians and nonagenarians. METHODS: Using cross-sectional analysis we assessed 95 very elderly persons (mean 85 years) living in the community. GFR was measured by iohexol (mGFR) and compared with estimates using six equations: MDRD, CKD-Epi_creatinine, CKD-Epi_cystatin, CKD-Epi_creatinine-cystatin, BIS_creatinine and BIS_creatinine-cystatin. RESULTS: Mean mGFR was 55 (range,19-86) ml/min/1.73 m(2). Bias was smaller with the CKD-Epi_creatinine-cystatin and the CKD-Epi_creatinine equations (-4.0 and 1.7 ml/min/1.73 m(2)). Accuracy (percentage of estimates within 30% of mGFR) was greater with the CKD-Epi_creatinine-cystatin, BIS_creatinine-cystatin and BIS_creatinine equations (85%, 83% and 80%, respectively). Among the creatinine-based equations, the BIS_creatinine had the greatest accuracy at mGFR < 60 ml/min/1.73 m(2) and the CKD-Epi_creatinine was superior at higher GFRs (79% and 90%, respectively). The CKD-Epi_creatinine-cystatin, BIS_creatinine-cystatin and CKD-Epi_cystatin equations yielded the greatest areas under the receiver operating characteristic curve at GFR threshold = 60 ml/min/1.73 m 2 (0.88, 0.88 and 0.87, respectively). In participants classified based on the BIS_creatinine, CKD-Epi_cystatin, or BIS_creatinine-cystatin equations, the CKD-Epi_creatinine-cystatin equation tended to improve CKD classification (net reclassification index: 12.7%, p = 0.18; 6.7%, p = 0.38; and 15.9%; p = 0.08, respectively). CONCLUSIONS: GFR-estimating equations CKD-Epi_creatinine-cystatin and BIS_creatinine-cystatin showed better accuracy than other equations using creatinine or cystatin C alone in very elderly persons. The CKD-Epi_creatinine-cystatin equation appears to be advantageous in CKD classification. If cystatin C is not available, both the BIS_cr equation and the CKD-Epi_cr equation could be used, although at mGFR < 60 ml/min/1.73 m(2), the BIS_cr equation seems to be the best alternative.

Detecção de podocitúria em pacientes com nefrite lúpica / Detection of podocyturia in patients with lupus nephritis

INTRODUÇÃO: A podocitúria tem sido detectada em doenças glomerulares, tais como em nefrite lúpica (NL), em que a proteinúria é uma manifestação importante, e sua ocorrência parece limitar-se à fase ativa da doença. OBJETIVO: Avaliar a podocitúria por imunofluorescência em pacientes portadores de NL e verificar possível associação com atividade clínica da doença. MÉTODOS: Foram avaliados 56 pacientes com NL. Os pacientes foram divididos em três grupos de acordo com o grau de atividade clínica: Grupo B, sem atividade (n = 17); Grupo C, com atividade discreta (n = 29) e Grupo D, moderada a grave (n = 10). Como grupo controle, foram incluídos 29 indivíduos saudáveis (Grupo A). A podocitúria foi estudada por meio de imunofluorescência indireta, usando-se anticorpos primários antipodocina, nefrina e sinaptopodina, e anticorpo secundário conjugado à FITC. Também foram avaliados os níveis de creatinina sérica e da relação proteína/creatinina (P/C) urinária, assim como a presença de hematúria e leucocitúria. RESULTADOS: A podocitúria com antipodocina e com antissinaptopodina correlacionou-se estatisticamente com a relação P/C (p = 0,001 e p = 0,013, respectivamente). Tanto a podocitúria com antipodocina, quanto a relação P/C, apresentaram correlação significante (p < 0,001) com a graduação de atividade da doença na NL, diferentemente do que se observou com os outros dois anticorpos, antinefrina e antissinaptopodina. CONCLUSÃO: Nossos achados sugerem que a pesquisa de podocitúria com anticorpos antipodocina poderia ser útil no acompanhamento de pacientes com NL, fornecendo dados relevantes quanto à atividade da doença.

INTRODUCTION: The podocyturia has been detected in glomerular diseases, such as lupus nephritis (LN), in which proteinuria is an important manifestation, and its occurrence seems to be limited to the active phase of the disease. OBJECTIVE: To evaluate podocyturia in LN patients, and the possible association with clinical disease activity. METHODS: We evaluated 56 patients with LN, that were classified in three groups according to the degree of clinical activity: Group B, no activity (n = 17), Group C with mild (n = 29) and Group D, moderate to severe activity (n = 10). The control group was composed by 29 healthy subjects (Group A). The podocyturia was studied by indirect immunofluorescence using primary antibodies to podocyte: anti-podocin, nephrin and synaptopodin, and a secondary antibody conjugated with FITC. We also evaluated serum creatinine levels, urinary protein/creatinine (P/C) ratio, hematuria and leucocituria. RESULTS: The podocyturia with anti-podocin and anti-sinaptopodin correlated statistically with the P/C ratio (p = 0.001 and p = 0.013, respectively). The podocyturia with anti-podocin, as well as the P/C ratio showed significant correlation (p < 0.001) with the degree of lupus disease activity, unlike the other two antibodies, anti-nephrin and anti-synaptopodin. CONCLUSION: Our findings show that podocyturia with anti-podocin could be useful in monitoring disease activity in LN patients.

Detection of podocyturia in patients with lupus nephritis.

INTRODUCTION: The podocyturia has been detected in glomerular diseases, such as lupus nephritis (LN), in which proteinuria is an important manifestation, and its occurrence seems to be limited to the active phase of the disease. OBJECTIVE: To evaluate podocyturia in LN patients, and the possible association with clinical disease activity. METHODS: We evaluated 56 patients with LN, that were classified in three groups according to the degree of clinical activity: Group B, no activity (n = 17), Group C with mild (n = 29) and Group D, moderate to severe activity (n = 10). The control group was composed by 29 healthy subjects (Group A). The podocyturia was studied by indirect immunofluorescence using primary antibodies to podocyte: anti-podocin, nephrin and synaptopodin, and a secondary antibody conjugated with FITC. We also evaluated serum creatinine levels, urinary protein/creatinine (P/C) ratio, hematuria and leucocituria. RESULTS: The podocyturia with anti-podocin and anti-sinaptopodin correlated statistically with the P/C ratio (p = 0.001 and p = 0.013, respectively). The podocyturia with anti-podocin, as well as the P/C ratio showed significant correlation (p < 0.001) with the degree of lupus disease activity, unlike the other two antibodies, anti-nephrin and anti-synaptopodin. CONCLUSION: Our findings show that podocyturia with anti-podocin could be useful in monitoring disease activity in LN patients.

Race adjustment for estimating glomerular filtration rate is not always necessary.

BACKGROUND: Estimated glomerular filtration rate (eGFR) is very important in clinical practice, although it is not adequately tested in different populations. We aimed at establishing the best eGFR formulas for a Brazilian population with emphasis on the need for race correction. METHODS: We evaluated 202 individuals with chronic kidney disease (CKD) and 42 without previously known renal lesions that were additionally screened by urinalysis. Serum creatinine and plasma clearance of iohexol were measured in all cases. GFR was estimated by the Mayo Clinic, abbreviated Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) formulas, and creatinine clearance was estimated by the Cockcroft-Gault (CG) formula. Plasma clearance of iohexol was used as the gold standard for GFR determination and for the development of a Brazilian formula (BreGFR). RESULTS: Measured and estimated GFR were compared in 244 individuals, 57% female, with a mean age of 41 years (range 18-82). Estimates of intraclass correlation coefficients among the plasma clearance of iohexol and eGFR formulas were all significant (p < 0.001) and corresponded to the following scores: CG 0.730; obesity-adjusted CG 0.789; Mayo Clinic 0.804; MDRD 0.848; MDRD1 (without race adjustment) 0.846; CKD-EPI 0.869; CKD-EPI1 (without race adjustment) 0.876, and BreGFR 0.844. CONCLUSIONS: All cited eGFR formulas showed a good correlation with the plasma clearance of iohexol in the healthy and diseased conditions. The formulas that best detected reduced eGFR were the BreGFR, CKD-EPI, and CKD-EPI1 formulas. Notably, the race correction included in the MDRD and CKD-EPI formulas was not necessary for this population, as it did not contribute to more accurate results.

Serum Beta 2-microglobulin/cystatin C index: a useful biomarker in lupus nephritis?

BACKGROUND: Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease with frequent flares. Our aim was to evaluate the beta 2-microglobulin/cystatin C (ß2M/CysC) index versus other markers as a predictor factor for assessment of SLE reactivation. METHODS: We prospectively analyzed 42 patients with lupus nephritis. Disease activity was classified using SLEDAI-2K and BILAG. Routine renal function and laboratory markers of SLE activity were performed, as well as serum ß2M (Sß2M)/serum CysC (SCysC) and Sß2M/serum creatinine (SCreat) indexes determinations. RESULTS: The 42 enrolled patients had a mean age of 37.7 ± 13.1 years, 88% were female and 67% Caucasians; mean estimated glomerular filtration rate was 61.9 ± 20.0 ml/min/1.73 m(2). There was a strong correlation between SCreat versus SCysC (r = 0.887), SCreat versus Sß2M (r = 0.865), and SCysC versus Sß2M (r = 0.880). Multivariate analysis showed that the Sß2M/SCreat index is a prognostic factor predicting active lupus nephritis. CONCLUSION: As SCysC is a good marker of renal function, it would be expected that the Sß2M/SCysC index could be a better indicator of renal activity than Sß2M/SCreat, but in the present study it did not add relevant clinical information in the assessment of renal activity in SLE.

Urinary protein/creatinine ratio versus 24-hour proteinuria in the evaluation of lupus nephritis.

INTRODUCTION: The urinary protein/creatinine ratio has been used instead of 24-hour proteinuria in Nephrology practice for the follow-up of glomerular diseases, considering the advantages of collection and the low cost. However, there are still doubts as to its applicability both for an isolated evaluation and for the follow-up of patients with lupus nephritis. OBJECTIVE: To evaluate 24-hour proteinuria determinations and random urine samples, performing urinary creatinine correction and urinary protein/creatinine ratio in subjects with lupus nephritis. METHODS: 24-hour proteinuria and urinary protein/creatinine ratio were determined by conventional methods (automated Pyrogallol for proteinuria and alkaline picrate for creatinine). RESULTS: Seventy-eight urine samples of 41 patients diagnosed with systemic lupus erythematosus, according to the American Rheumatology Association, with lupus nephritis, were analyzed, and a good correlation between 24-hour proteinuria and urinary protein/creatinine ratio (r = 0.9010 and r² = 0.813) was observed. However, a poor correlation between random proteinuria (without creatinine correction) versus 24-hour proteinuria (r = 0.635 and r² = 0.403) or versus urinary protein/creatinine ratio (r = 0.754 and r² = 0.569) was seen. CONCLUSION: 24-hour proteinuria and urinary protein/creatinine ratio were useful in the follow-up of each case. However, we observed that the absolute values were different, which did not allow the replacement of one for the other during follow-up, especially when this result is used to define the activity of the disease. Based on these results, we suggest a period of intersection from one to the other (two to three determinations by both methods), and the choice of one marker for proteinuria follow-up, if necessary.

Relação proteína/creatinina na urina versus proteinúria de 24 horas na avaliação de nefrite lúpica / Urinary protein/creatinine ratio versus 24-hour proteinuria in the evaluation of lupus nephritis

INTRODUÇÃO: Tem-se defendido a utilização do índice urinário proteína e creatinina em substituição à determinação de proteinúria de 24 horas para acompanhamento de doenças glomerulares, considerando-se as vantagens de maior facilidade na coleta e o menor custo. Entretanto, há dúvidas quanto à pertinência de usar este índice tanto numa avaliação isolada como no seguimento de pacientes com nefrite lúpica. OBJETIVO: Avaliar as determinações de proteinúria de 24 horas e proteinúria em amostra isolada de urina, fazendo a correção pela creatinina urinária, relação proteinúria/creatininúria, em indivíduos com nefrite lúpica. MÉTODOS: Determinações de proteinúria de 24 horas e relação proteinúria/creatininúria por métodos convencionais (Pirogalol automatizado para proteinúria e picrato alcalino para creatinina). RESULTADOS: Foram comparadas 78 amostras de urina de 41 pacientes com diagnóstico de lúpus eritematoso sistêmico, segundo os critérios da Associação Americana de Reumatologia, com nefrite lúpica, constatando-se uma boa correlação entre proteinúria de 24 horas e relação proteinúria/creatininúria (r = 0,9010 e r² = 0,813). Não se observou, entretanto, uma boa correlação entre proteinúria em amostra isolada (sem correção pela creatinina urinária) versus aquela de 24 horas (r = 0,635 e r² = 0,403) ou versus relação proteinúria/creatininúria (r = 0,754 e r² = 0,569). CONCLUSÃO: Os marcadores de proteinúria de 24 horas e relação proteinúria/creatininúria isoladamente mostraram-se úteis no acompanhamento de cada caso. Porém, observou-se que os seus valores absolutos são diferentes, não possibilitando a substituição de um pelo outro ao longo do seguimento, particularmente quando este resultado é usado para definição de atividade da doença. Se necessário, sugere-se um período de intersecção (duas a três determinações pelos dois métodos) para mudança de um para outro e escolha de um único marcador preferencial para seguimento da proteinúria.

INTRODUCTION: The urinary protein/creatinine ratio has been used instead of 24-hour proteinuria in Nephrology practice for the follow-up of glomerular diseases, considering the advantages of collection and the low cost. However, there are still doubts as to its applicability both for an isolated evaluation and for the follow-up of patients with lupus nephritis. OBJECTIVE: To evaluate 24-hour proteinuria determinations and random urine samples, performing urinary creatinine correction and urinary protein/creatinine ratio in subjects with lupus nephritis. METHODS: 24-hour proteinuria and urinary protein/creatinine ratio were determined by conventional methods (automated Pyrogallol for proteinuria and alkaline picrate for creatinine). RESULTS: Seventy-eight urine samples of 41 patients diagnosed with systemic lupus erythematosus, according to the American Rheumatology Association, with lupus nephritis, were analyzed, and a good correlation between 24-hour proteinuria and urinary protein/creatinine ratio (r = 0.9010 and r² = 0.813) was observed. However, a poor correlation between random proteinuria (without creatinine correction) versus 24-hour proteinuria (r = 0.635 and r² = 0.403) or versus urinary protein/creatinine ratio (r = 0.754 and r² = 0.569) was seen. CONCLUSION: 24-hour proteinuria and urinary protein/creatinine ratio were useful in the follow-up of each case. However, we observed that the absolute values were different, which did not allow the replacement of one for the other during follow-up, especially when this result is used to define the activity of the disease. Based on these results, we suggest a period of intersection from one to the other (two to three determinations by both methods), and the choice of one marker for proteinuria follow-up, if necessary.

Are serum cystatin C levels influenced by steroid doses in lupus nephritis patients?

INTRODUCTION: Cystatin C is considered a promising test to evaluate glomerular filtration rate, since it has characteristics of an ideal endogenous marker, being similar or even superior to serum creatinine according to some studies. However, it is possible that some factors (as corticotherapy) could have an influence on serum cystatin C levels regardless of the glomerular filtration rate. The aim of this study was to investigate if different doses of glucocorticoid could have an influence on serum cystatin C levels in lupus nephritis patients. METHODS: We evaluated 42 patients with lupus nephritis that performed 109 different blood collections; their mean age was 37.7 ± 13.1 years old, and 88% were female; the mean estimated glomerular filtration rate was of 61.9 ± 20.0 mL/min. Patients were divided according to their glucocorticoid dose in two groups: A - high (pulse therapy with methylprednisolone and prednisone > 0.5 mg/kg/d, n = 14) versus B - low doses (prednisone ≤ 0.5 mg/kg/d, n = 28). Serum creatinine levels were used as parameters for renal function comparison. Cystatin C was determined by an in-house methodology, using Luminex system flow citometry. RESULTS: Considering these groups, cystatin C levels were different only in the second visit (p = 0.106). But, when the serum creatinine levels were considered in the same groups, a marginally significant difference among them (p = 0.070) was observed, which suggested that the difference in cystatin C levels between the groups was caused by their respective glomerular filtration rate. There was not any difference between those groups that received or did not receive pulse therapy. CONCLUSION: Although some previous studies have shown that glucocorticoid has an influence on serum cystatin C levels, we have not observed such interference in the lupus nephritis patients submitted to corticotherapy.

Are serum cystatin C levels influenced by steroid doses in lupus nephritis patients? / Os níveis séricos de cistatina C sofrem influência da dose de corticoide em pacientes com nefrite lúpica?

INTRODUÇÃO: A cistatina C é considerada como um teste promissor para avaliar a taxa de filtração glomerular, pois apresenta características de um marcador endógeno ideal, sendo similar ou até superior à creatinina sérica, segundo alguns estudos. No entanto, é possível que alguns fatores (como corticoterapia) influenciem os níveis séricos da cistatina C, independente da taxa de filtração glomerular. Procurouse investigar se diferentes doses de glicocorticoides afetariam os níveis do marcador em pacientes com nefrite lúpica. MÉTODOS:Foramavaliados42pacientescom nefrite lúpica, submetidos a 109 coletas de sangue diferentes; a idade média deles era de 37,7 ± 13,1 anos, e 88 por cento eram do sexo feminino; a taxa de filtração glomerular estimada média era de 61,9 ± 20,0 mL/min. Os pacientes foram divididos, de acordo com a dose de corticoide, em dois grupos: A - altas (pulsoterapia com metilprednisolona e prednisona > 0,5 mg/kg/dia, n = 14) versus B - baixas doses (prednisona ≤ 0,5 mg/kg/dia, n = 28). Os níveis de creatinina sérica foram usados como parâmetros de comparação em relação à função renal. A cistatina C foi determinadapor metodologia desenvolvida in-house, usando citometria de fluxo na plataforma Luminex. RESULTADOS: Considerando esses dois grupos, os níveis de cistatina C foram diferentes apenas nas amostras da segunda consulta (p = 0,106). Mas, quando considerados os níveis de creatinina sérica nos mesmos grupos, foi observada uma diferença marginalmente significante entre eles (p=0,070), sugerindo que a diferença nos níveis de cistatina C entre os grupos foi causada por suas respectivas taxas de filtração glomerular. Não houve diferença entre os que receberam, ou não, pulsoterapia. CONCLUSÕES: Embora alguns estudos tenham mostrado que os glicorticoides podem influenciar os níveis de cistatina C, não foi observada tal interferência nesta população de pacientes com nefrite lúpica submetidos à corticoterapia.

INTRODUCTION: Cystatin C is considered a promising test to evaluate glomerular filtration rate, since it has characteristics of an ideal endogenous marker, being similar or even superior to serum creatinine according to some studies. However, it is possible that some factors (as corticotherapy) could have an influence on serum cystatin C levels regardless of the glomerular filtration rate. The aim of this study was to investigate if different doses of glucocorticoid could have an influence on serum cystatin C levels in lupus nephritis patients. METHODS: We evaluated 42 patients with lupus nephritis that performed 109 different blood collections; their mean age was 37.7 ± 13.1 years old, and 88 percent were female; the mean estimated glomerular filtration rate was of 61.9 ± 20.0 mL/min. Patients were divided according to their glucocorticoid dose in two groups: A - high (pulse therapy with methylprednisolone and prednisone > 0.5 mg/kg/d, n = 14) versus B - low doses (prednisone ≤ 0.5 mg/kg/d, n = 28). Serum creatinine levels were used as parameters for renal function comparison. Cystatin C was determined by an in-house methodology, using Luminex system flow citometry. RESULTS: Considering these groups, cystatin C levels were different only in the second visit (p = 0.106). But, when the serum creatinine levels were considered in the same groups, a marginally significant difference among them (p = 0.070) was observed, which suggested that the difference in cystatin C levels between the groups was caused by their respective glomerular filtration rate. There was not any difference between those groups that received or did not receive pulse therapy. CONCLUSION: Although some previous studies have shown that glucocorticoid has an influence on serum cystatin C levels, we have not observed such interference in the lupus nephritis patients submitted to corticotherapy.