Long-term effect of captopril on kidney function in various forms of hypertension.

To study long-term effects of captopril on renal function in patients with various forms of severe hypertension, serum creatinine values were monitored in 76 patients under captopril therapy over a period of up to 3 years. Three different groups were formed: (1) patients with essential hypertension (n=37); (2) patients with renovascular hypertension (n=20); (3) patients with renal parenchymatous hypertension (n=19). In each of the three groups reduction in blood pressure was accompanied by increases in serum creatinine. However, both changes were more pronounced in patients with renovascular hypertension. In this group only the rise in creatinine was statistically significant and showed a slight progression with duration of captopril treatment. Group specific analysis revealed that the increase was smaller in patients with unilateral (n=16) renovascular disease than in those with bilateral (n=4) involvement, but in the former it was still significantly higher than in patients with essential or renal parenchymatous hypertension. Separation of patients according to the underlying disease of renovascular hypertension showed that renal function deteriorated less in patients with arteriosclerotic origin (n=10) than in those with fibromuscular dysplasia (n=8). Statistical evaluation of subjects with renovascular and essential hypertension still revealed significant differences in creatinine when the patients with initial plasma renin activity (PRA) below and above 6 ng/ml·3 h were compared separately. A significant correlation (r=0.73;P<0.05) between blood pressure reduction and creatinine changes was obtained only for patients with renovascular hypertension. Finally, in all three groups of patients creatinine changes were statistically independent from daily dosages of captopril. From these data we conclude that sustained impairment of kidney function by captopril is mainly restricted to patients with renovascular hypertension and possibly results from the combined effects of low renal perfusion pressure and interference with intrarenal regulation of glomerular filtration rate by a postulated angiotensin-II-mediated mechanism.