Urinary Kallikrein Excretion in Chronic Renal Failure: Relationship to Blood Pressure and the Acute Effect of Captopril

Previous studies of the renal kallikrein-kinin system in chronic renal failure (CRF) have given conflicting results. We have assessed activity of this vasoactive hormone system in CRF and investigated a possible relationship to hypertension in patients with CRF: 24-hour urinary kallikrein excretion (Uka) was measured in 22 patients with CRF (9 normotensive and 13 hypertensive) and 11 healthy controls. Age, sex, urine volume, and urinary sodium excretion were similar in each group. Compared with controls, Uka was reduced in both normotensive and hypertensive patients with CRF, with no difference between CRF groups. The reduction in Uka in CRF was less than the reduction in glomerular filtration rate (GFR), as assessed by endogenous creatinine clearance (Ccr). When Uka was divided by Ccr, Uka/mL Ccr was therefore increased, to a similar extent, in both normotensive and hypertensive patients with CRF. This suggests that release of renal kallikrein from functioning nephrons is increased in CRF. The results do...