1989 Volume 32 Issue 7 Pages 503-510
In order to evaluate diabetic nephropathy, five proteins with different molecular weights and isoelectric points were measured by RIA in urine samples of controls and diabetic patients without clinical nephropathy after water loading test. The degree of diabetic nephropathy was divided into three groups according to the maximum urinary albumin excretion rate (U-AERmax) after water loading test: group 1 (U-AERmax <15μg/min), group 2 (15-100μg/min), and group 3 (>100μg/min).
The ratio of orosomucoid to U-AERmax in group 1 was significantly higher than that in the control sample, though the ratio of lambda free light chain to U-AERmax was not significant in either group. The results suggest that the charge selectivity loss of the glomerular basement membrane (GBM) may occur in the group 1stage, because orosomucoid and lambda free light chain have similar molecular weights with different isoelectric points. Furthermore, the leakage of IgG, which has a large molecular weight, was significantly increased in group 3. This result indicates that pore size selectivity loss in the GBM may exist in group 3. These findings suggest that the water loading test might be useful in analyzing the severity of diabetic nephropathy.
