Changes in Plasma and Extracellular Fluid Volumes in Patients with Essential Hypertension During Long-Term Treatment with Hydrochlorothiazide

Abstract

In 13 untreated patients with essential hypertension, the plasma volume (T-1824) and the extracellular fluid volume ( 82 Br - distribution space) were determined three times. During treatment with 50 to 100 mg of hydrochlorothiazide daily, determinations of plasma volume and extracellular fluid volume were repeated after treatment for 1 mo (13 patients), 2 mo (13 patients), 4 mo (eight patients), and 6 mo ( seven patients). In all cases the average plasma and extracellular fluid volumes were reduced compared with the averages of three control values. The plasma volume was significantly reduced at the 5% level after treatment for 1, 2, and 4 mo. Corresponding studies from the literature have been reviewed and, on the basis of these studies and our own results, it is concluded that thiazides have a volume-depleting effect which is continued during long-term treatment of patients with essential hypertension.