Characterization of an experimental model of progressive renal disease in rats

ABSTRACT PURPOSE: To characterize an experimental model of progressive renal disease induced by different degrees of nephrectomy in rats. METHODS: Eighty male Wistar rats were divided into four experimental groups (n=20/group): sham surgery (control group), progressive degrees of nephrectomy leading to mild uremia (group 1), moderate uremia (group 2) and severe uremia (group 3). Ten animals of each group were followed for two or four weeks. At the end, blood and 24-hour urine samples were collected to determine renal function parameters. Urine output and water and food intake were daily monitored. RESULTS: In rats of group 1, serum levels of creatinine and urea and microalbuminuria were increased, while reduced creatinine clearance (p<0.05, compared with control group), without changing blood pressure. Animals of group 2 had more accentuated alterations: increases in urinary output, blood pressure, serum concentrations of urea, creatinine, sodium, potassium, and in microalbuminuria, and reduction of creatinine clearance (p<0.05). Group 3 exhibited even more increased serum concentrations of urea, creatinine, sodium and potassium, blood pressure and microalbuminuria, and decreased creatinine clearance (p<0.05) in comparison with control group and unilateral nephrectomy. CONCLUSION: Progressive nephrectomy in rats seems to be useful to study the physiopathology of chronic kidney disease and its mechanisms of progression.

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.

Presença de microalbuminúria como fator de risco em pacientes diabéticos portadores de doença arterial coronária estável / Microalbuminuria as a risk factor in diabetic patients with stable coronary artery disease

A microalbuminúria é admitida como o principal marcadorpara o desenvolvimento de nefropatia diabética. Sua presençatambém é preditora independente de morbidade e mortalidadecardiovasculares. A relação da microalbuminúria com fatoresde risco clássicos para a doença multiarterial coronária (DAC)também tem sido mostrada em estudos epidemiológicos. Opresente estudo tem o objetivo de determinar a prevalênciade microalbuminúria em um grupo de pacientes diabéticosportadores de DAC e relacionar a sua presença com os fatoresclássicos de risco cardiovascular. Trata-se de um estudotransversal realizado com pacientes diabéticos portadoresde DAC, que realizam tratamento no Instituto do Coração(InCor-HCFMUSP). Foram avaliados os seguintes parâmetros:idade, presença ou ausência de HAS, tempo de diabetes,tabagismo, perfil lipídico, hemoglobina glicada e presença demicroalbuminúria/proteinúria, a partir da coleta urinária em24 horas. Os pacientes foram estratificados em três grupos,conforme o valor de albuminúria. Foram feitas análisesestatísticas comparando as diferentes variáveis entre os trêsgrupos. Nesta amostra de pacientes portadores de DM e DACmultiarterial estável, observou-se uma relação crescente entreos valores de albuminúria e o tempo de diabetes mellitus, níveisséricos de LDL-colesterol e triglicérides.

Microalbuminuria is accepted as a surrogate marker for thedevelopment of diabetic nephropathy. Its presence is alsoan independent predictor of cardiovascular morbidity andmortality. The relationship of microalbuminuria with classicrisk factors for coronary multivessel disease (CAD) has alsobeen shown in epidemiological studies. The present studyaims to determine the prevalence of microalbuminuria ina group of diabetic patients with CAD and correlate theirpresence with the classic cardiovascular risk factors. This isa cross-sectional study with diabetic patients with CAD whoperform treatment at the Heart Institute (Incor-HCFMUSP).We evaluated the following parameters: age, presence orabsence of hypertension, duration of diabetes, smoking, lipidprofile, glycated hemoglobin and microalbuminuria/proteinuriafrom urine collection in 24 hours. Patients were stratified into3 groups according to the value of albuminuria. Statisticalanalyzes were performed comparing the different variablesamong the three groups. In this sample of patients with diabetesand stable multivessel CAD there was a growing relationshipbetween the values of albuminuria and duration of diabetesmellitus, serum LDL-cholesterol and triglycerides.