[Microalbumin excretion in the group of patients with asymptomatic hematuria]

Urine albumin was determined in patients with chronic glomerular injuries with normal renal function, who had shown positive test of microhematuria but negative test of proteinuria at any time of our renal clinic. The subjects were divided into 4 groups: (1) IgA nephropathy (IgAN); 13, (2) asymptomatic hematuria (AS); 18, (3) nephrotic syndrome in complete remission (CR); 21 and (4) age matched normal subjects; 44. Urine albumin concentration was measured with radioimmunoassay in the ambulatory urine, and, in some cases, in the urine obtained after supine position for 30 minutes to demonstrate the effect of ambulatory physical movement on albumin excretion. Also urine alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) were estimated by monitoring the absorbance of products released by the enzyme, as the indices of tubular function. The results indicated that urine albumin were 8.4 +/- 7.3 mg/g Cr (Mean +/- SD) in normal subjects, and 8.8 +/- 8.9 mg/g Cr in CR (vs. controls: N.S.), 18.9 +/- 14.5 mg/g Cr in AS (P = 0.0071), and 22.2 +/- 14.9 mg/g Cr in IgAN (P = 0.0063). The albumin excretion had no relation with the grade of microhematuria and also with the ambulatory physical movement. Moreover, AAP and NAG excretion in each group had shown no significant alterations. These results indicate that urine albumin increases in IgAN and AS with normal renal function and with microhematuria alone, but not in CR. Urine albumin is probably glomerular origin, since no abnormality is found in the tubular functions.