ENZYMURIA IN NON-INSULIN DEPENDENT DIABETIC PATIENTS: SIGNS OF RENAL TUBULAR CELL DYSFUNCTION
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In this study we measured the 24 hours urinary activity of two renal tubular enzymes; N-acetyl fl-D-glucosaminidase (NAG) and y-glutamyl transpeptidase (GGTP) that originate from renal proximal tubular cells, in addition to 24 hours urinary excretion of 132-microglobulin to evaluate renal tubular function in 33 noninsulin dependent diabetic patients (NIDD patients) recently discovered and not yet treated from diabetes mellitus. For all these diabetics fasting and 2 hours post prandial blood sugar were evaluated, in addition to estimation of glycosylated haemoglobin and urinary albumin in 24 hours, and these diabetic patients were classified into 3 subgroups according to their urinary albumin excretion/24 hours; (I) 12 diabetics with normoalbuminuria (urinary albumin <30 mg/24 hours); (2) 11 diabetics with microalbuminuria (urinary albumin from 30-300 mg/24 hours); (3) 10 diabetics with macroalbuminuria (urinary albumin >300 mg/24 hours). Fifteen apparently healthy volunteers were taken as normal controls. And we get the following results: - The urinary activity of NAG was significantly increased while that of GGTP was significantly decreased in all diabetic subgroups compared to control subjects (P4).01) and in diabetics with either micro-or macroalbuminuria compared to diabetics with normoalbuminuria (P<0,01) and in diabetics with macroalbuminuria compared to diabetics with microalbuminuria (P<0.01). - Urinary 132-microglobulin increased significantly only in diabetics with macroalbuminuria compared to controls and to other diabetic subgroups (P<0.01). - NAG correlated significantly positive while GGTP correlated significantly negative with fasting blood sugar (r=0.508, P<0.01 and r = -0.491, P<0.01 respectively), glycosylated haemoglobin (r = 0.552, P<0.01 and r = -0.481 P<0.01 respectively), and urinary albumin (r=0.527, P<0.01 and 1=-0.475, P<0.01 respectively), in all NID diabetics. From this study we conclude that there is renal tubular cell dysfunction in non-insulin dependent diabetic patients as evidenced by these changes in the enzyme activity of both NAG and GGTP in 24 hours urine, in addition to 24 hours urinary excretion of 132 microglobulin and this tubular dysfunction may precede glomerular alterations as evidenced by the significant changes in these urinary enzymes activities even in the normoalbuminuric diabetics. And we recommend measurement of these renal tubular cell enzymes as markers of renal tubular cell dysfunction. Their measurement is non-invasive and inexpensive. In addition we also recommend early and proper management of diabetes as this will reverse the renal tubular cell dysfunction in the early stage of the disease.