Effects of Long-term Antihypertensive Treatment and Aging on Renal Function and Albumin Excretion in Primary Hypertension

The effects on renal function and urinary albumin excretion of 7 years of antihypertensive treatment compared to the effects of normal aging were studied in a random sample of 40 men with newly diagnosed primary hypertension and in 17 normotensive men of the same age, respectively. The hypertensives were treated with metoprolol either as monotherapy (n = 21) or combined with hydrochlorothiazide or hydralazine. Glomerular filtration rate (GFR; inulin clearance), renal blood flow (RBF; para-aminohippurate clearance), renal vascular resistance (RVR), and the 24 h urinary albumin excretion were determined. GFR was significantly reduced from 104 +/- 15 mL/min (mean +/- SD) to 86 +/- 20 mL/min (P < .001) in the hypertensive group, but the reduction was not significantly greater than in the normotensive group. As judged from the study of a subgroup of the hypertensives, most of the decrease in GFR occurred early as an immediate drug-induced, functionally explained decrease. The changes in RBF and RVR after 7 years of treatment did not differ significantly from those due to normal aging. RVR remained higher and RBF remained lower in the hypertensives than in the normotensives. The urinary albumin excretion in the hypertensives was significantly reduced after 7 years but remained higher than in the normotensives. In conclusion, the changes in renal function and hemodynamics seen after long-term treatment with metoprolol in primary hypertension were not significantly different from the changes caused by normal aging in normotensives.