Renal function before and after withdrawal of long term antihypertensive treatment in primary hypertension.

Glomerular filtration rate (GFR) and renal plasma flow (inulin and para-aminohippurate clearance) were measured in a random sample of 17 normotensive and 20 untreated patients with primary hypertension. At the 7-year follow-up, 19 patients were on metoprolol (as the sole drug or in combination with either hydrochlorothiazide or hydralazine) and 1 patient was on hydrochlorothiazide. They were re-examined after withdrawal of treatment and return of hypertension. At the 7-year follow-up GFR was more reduced in the hypertensive (-17%) than in the normotensive group (-9%). The percentage decrease in renal blood flow was the same in both groups. No significant renal function changes appeared after withdrawal of treatment. In conclusion, there was a slightly greater deterioration in GFR in the hypertensive patients after long term treatment with metoprolol than can be explained by normal ageing.