Abstract
A highly sensitive RIA for albumin was developed and urinary excretion of albumin was determined in 29 diabetics (DM), who had no proteinuria by routine urinalysis, and in 30normal subjects (N). Glycated albumin (GA) in serum and urine as well as urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) were also estimated. The 24 hour urinary albumin excretion in N ranged from 4.0 to 12.9 mg/day (mean +SD,7.3±2.8), and the albumin excretion averaged 16.5±13.7 in DM, which was significantly higher than that in N. A significantly positive correlation existed between albumin excretion rate (μg/min, AER) and the first morning urinary albumin index (mg/g creatinine, AI), suggesting that Al is a good predictor of AER.
The mean values of Al and of NAG index (U/g⋅creatinine) were apparently elevated in DM, however, no significant relation was found between Al and NAG index. The urinary GA/serum GA ratio was decreased in DM prior to the elevation of urinary albumin excretion and these returned to normal by metabolic control. These results suggest that the selectivity of urinary GA excretion is an indicator of the glomerular changes at the early stage of diabetic nephropathy.
