Effects of reduction in dose and discontinuation of hydrochlorothiazide in patients with controlled essential hypertension.

We studied the effects of a reduction in dose of hydrochlorothiazide from 50 to 25 mg/d, and its discontinuation for up to 22 months in 36 well-controlled hypertensive patients. Hydrochlorothiazide was discontinued if the diastolic blood pressure remained less than or equal to 94 mm Hg after a 6-month period on the lower dose of hydrochlorothiazide. No other changes were made in medications or diet. Sitting systolic blood pressure rose from 135 +/- 15 mm Hg to 140 +/- 14 mm Hg on reduction of the hydrochlorothiazide dose and rose still further to 145 +/- 20 mm Hg on discontinuation. Even greater increases in standing blood pressure were observed. There were no significant effects on the diastolic blood pressure with reduction of dose or discontinuation of hydrochlorothiazide. A significant decrease in the serum uric acid and a rise in serum potassium occurred. There were no changes in serum glucose or lipids on reduction in the dose of hydrochlorothiazide; whereas, with discontinuation, the serum lipids and hemoglobin A1C fell significantly. These results suggest that the benefits of a reduced dose of hydrochlorothiazide may not be as great as considered heretofore.