HUMAN URINARY INTESTINAL ALKALINE-PHOSPHATASE AS AN INDICATOR OF S3-SEGMENT-SPECIFIC ALTERATIONS IN INCIPIENT DIABETIC NEPHROPATHY

Urinary enzymes were determined in a controlled study including 28 typ e I diabetes mellitus patients. Fifteen patients had persistent microa lbuminuria and were compared to 13 normoalbuminuric patients with comp arable age and sex distribution. All patients had normal renal functio n as measured by serum creatinine. Human intestinal alkaline phosphata se (hIAP), a specific marker of the proximal tubular S3 segment, was e levated in the urine of microalbuminuric patients while human tissue n on-specific alkaline phosphatase (hTNAP), indicating effects mainly at the S1-S2 segments, was not. Urinary hIAP was correlated with serum g lycated haemoglobin. These results suggest that tubular alterations ar e present at an early stage of diabetic nephropathy, especially at the S3 segment, and that hIAP may have promise as an early marker.