Urinary biomarkers in the early diagnosis of renal damage in diabetes mellitus patients

Abstract

PURPOSE: The aim of this study was to determine the prevalence of tubular enzymes such as N-acetyl-β-D-glucosaminidase (NAG), alanine aminopeptidase (AAP) and gamma glutamyl transferase (γ-GT), α1-microglobulin, β2-microglobulin (β2-M) as well as microalbuminuria among patients with diabetes mellitus. MATERIAL AND METHODS: Biomarkers were evaluated in 285 type 1 diabetes mellitus patients and 30 healthy volunteers as a control group. Urinary levels of tubular enzymes such as NAG, AAP and γ-GT as well as microalbuminuria, α1-microglobulin and β2-M were determined by routine methods. Diabetes mellitus patients were divided into two groups - with normoalbuminuria (3-30 mg/L) and microalbuminuria (31-300 mg/L). RESULTS: Compared with healthy individuals, diabetes mellitus patients with normoalbuminuria excreted significantly higher levels of urinary NAG (p<0.05). In patients with microalbuminuria, the most significant changes of urinary NAG, AAP and g-GT, serum cystatin C and β2-M (p<0.001) were established. There was no significant difference between the patients and controls in respect to serum/urine creatinine. Urinary α1-microglobulin level was higher in the patients with poor glucose control (HbA1c >8.5%) and directly related to albuminuria. A significantly decrease of creatinine clearance in these patients was found out, too. CONCLUSION: Measuring the urinary NAG excretion, α1-microglobulin and cystatin C could be useful for the assessment of renal failure in diabetes mellitus patients. The activity of AAP and γ-GT is a less sensitive indicator of tubular lesions. The levels of β2-M and cystatin C which diagnostic accuracies are superior to those of serum creatinine represent early indicators of incipient diabetic nephropathy. Therefore, urinary biomarkers are useful in early detection of tubular and glomerular lesions in type 1 diabetes mellitus patients. Scripta Scientifica Medica 2013; 45(3): 58-64.