Effect of thiazide-based therapy on serum alkaline phosphatase. Hypertension Detection and Follow-up Group

This study reports a correlation of alkaline phosphatase (AP) with diastolic blood pressure (DBP), and a reduction of alkaline phosphatase after chlorthalidone therapy that reached a nadir at three years of therapy, then gradually returned toward, but not reaching, baseline values. The data is from the baseline examination and follow-up of 3928 initially untreated stepped-care patients in the Hypertension Detection and Follow-up Program. In multiple regression analysis, both age and DBP were significantly correlated with increased AP in males and females. After initiation of therapy with chlorthalidone, AP levels fell progressively until the third year, when they were reduced by 11 +/- 15 IU in the males and 14 +/- 15 IU in the females. The data are compatible with the interpretation that thiazide-induced reduction in urinary calcium excretion has led to a more positive calcium balance and reduction of bone turnover, and suggests that a beneficial effect of thiazide-based antihypertensive therapy could be decreased osteoporosis.