Tubular function in diabetic children assessed by Tamm-Horsfall protein and glutathione S-transferase
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- Holmquist, P. & Torffvit, O. Pediatr Nephrol (2008) 23: 1079. doi:10.1007/s00467-008-0770-9
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In a previous study, we found urinary excretion of Tamm-Horsfall protein (THP) to be persistently decreased in 25% of patients during the first year after diagnosis of diabetes mellitus. We thus wanted to study another marker for distal tubular function, pi glutathione S-transferase (π-GST) and compare this and THP with proximal tubular function evaluated with α-GST and α-1-microglobulin (HC) in patients with longer duration of diabetes. One hundred and eighty-four diabetic and 16 control children were studied with timed overnight urine collections. Median age was 14 years, and median age at diagnosis was 8 years. The urinary excretion of α- and π-GST was significant lower in diabetic than control children. There were no differences in the excretion of HC and THP. Diabetic children with decreased α-GST had higher albumin excretion, HbA1c levels, and longer diabetes duration but decreased THP excretion and cystatin-C clearance compared with those with normal excretion. In contrast, a decreased π-GST or THP excretion was not associated with such differences. Diabetic children with increased HC excretion had increased HbA1c levels. Diabetic children, before the stage of microalbuminuria, may have signs of both proximal and distal tubular dysfunction, which is related to diabetes duration and poor metabolic control. Alpha-GST and π-GST seem to be more sensitive than other parameters studied.