Investigação laboratorial da nefropatia diabética: avaliação de marcadores tubulares e do impacto da correção pela creatinina urinária

Abstract

Diabetic nephropathy (DN) is a multifactorial patholgy, characterized by the increased presence of albumin in urine. Currently, urinary albumin (uAlb) is a marker for glomerular damage mostly used for the diagnosis of DN; however, some reports in the literature showed that patients might exhibit histological signs of DN and normal uAlb. Markers of tubular damage have shown great ability to diagnose DN prior to onset of uAlb stages. Urinary markers can be adjusted by urinary creatinine (uCr), to compensate for the daily excretion rates; nevertheless, these standards are not fully established. Thus, the aim of this study was to evaluate the diagnostic ability of the markers of tubular damage NAG, GGT, NAP, KIM-1 and NGAL and the influence of the correction for uCr in DN. Glycemic control, lipid and hepatic enzyme profile as well urinary markers of glomerular and tubular damage were assessed in type 2 DM patients stratified into two groups regarding the existence of DN. The tubular markers evaluated in this study were higher in type 2 DM patients with DN compared to type 2 diabetes without DN for both markers expressed in absolute values or as a ratio to the uCr. When analyzing the areas under the curve (AUROC) obtained, we find that all markers, except for GGT expressed in absolute values, have the ability to identify the ND. NGAL and KIM-1, when expressed in absolute values had better diagnostic ability (AUROC> 0.9, sensitivity and specificity> 90%). NAG, GGT and NAP were when expressed in ratio had the best diagnostic capability, with AUROC equal to 0.683, 0.783 and 0.850, respectively. Stratifying patients into groups according to urinary albumin excretion (UEA), we found that NGAL and KIM-1 already showed increased levels in UEA range 10 - 30 mg/g cr. In addition to being, GGT showed an association with glomerular hyperfiltration Individuals in type 2 DM without nephropathy. Urinary tubular markers used in the study have potential value in diagnosis, especially NGAL and KIM-1 that showed the best diagnostic features, and are early markers of DN type 2 DM patients.