Urinary sulphated glycosaminoglycans and Tamm-Horsfall protein in type 1 diabetic patients

Objective: In diabetic nephropathy there is a decrease in glycosaminoglycan s (GAG) in basement membranes and in Tamm-Horsfall protein (THP) in the dis tal tubules of the kidneys. Since GAG is present in both glomerular and tub ular basement membranes, and the synthesis of both GAG and THP involves gly cosylation, this study was carried out in order to investigate whether urin ary excretion of these substances is interrelated. Material and Methods: 24 -h urinary collections were analysed. A total of 94 diabetic patients were grouped in accordance with the urinary albumin excretion rare as normo- (<2 0 mu g/min) (n = 35), micro- (20-200 mu g/min) (n = 30) and macroalbuminuri a (>200 mu g/min) (n = 29). Results: In comparison with 26 control subjects , the excretion rate of GAG was decreased in patients with micro- and macro albuminuria and excretion of Tamm-Horsfall protein in patients with macroal buminuria. The excretion rates of GAC and THP were associated (r = 0.64, p < 0.001) and correlated with creatinine clearance (r = 0.46 and r = 0.53, p < 0.001; respectively) but not with levels of HbA(1c). Conclusions: In con clusion, albuminuria was associated with decreased urinary excretion of sul phated GAGs, which was associated with the excretion rate of Tamm-Horsfall protein, indicating that excretion of GAG was associated with distal tubula r dysfunction in diabetic patients.