Urinary excretion of dipeptidyl aminopeptidase i.v. in patients with renal diseases.

Enzymuria is a frequent finding in patients suffering from various kidney diseases. The present study was undertaken to evaluate the clinical value of the determination of tubule-brush-border-associated dipeptidyl aminopeptidase IV (DAP IV) in the urine of patients with acute and chronic tubulointerstitial nephritis (n = 12), chronic glomerulonephritis (n = 15), essential arterial hypertension (n = 30), after kidney transplantation (n = 20), and of healthy control persons (n = 68). DAP IV was measured in spontaneously voided mid-stream morning urine ("second morning urine"), and was expressed as enzyme activity in units/liter. In order to account for variations due to urine concentration without collecting 24-hour specimens, a urinary DAP IV/creatinine ratio (DCR) was calculated. Furthermore, patterns of proteinuria were assayed by SDS-polyacrylamide gel electrophoresis. Urinary DAP IV activity of healthy controls was 4.94 +/- 0.12 U/l (DCR: 0.46 +/- 0.30 U/mmol creatinine) with only small day to day variations. Urinary DAP IV activity in patients with tubulointerstitial nephritis was significantly higher (15.5 +/- 15.6 U/l, p less than 0.05 vs controls; DCR: 1.67 +/- 0.97 U/mmol creatinine, p less than 0.001 vs controls). In patients with chronic glomerulonephritis urinary DAP IV activity was 9.6 +/- 5.6 U/l, p less than 0.05 (DCR: 1.22 +/- 0.75 U/mmol creatinine, p less than 0.05 vs controls). Increased urinary DAP IV activity in patients with chronic glomerulonephritis was associated with a mixed glomerulo-tubular pattern of proteinuria (as determined by SDS-PAGE).(ABSTRACT TRUNCATED AT 250 WORDS)