Comparative Effects of Nitrendipine and Hydrochlorothiazide on Calciotropic Hormones and Bone Density in Hypertensive Patients

The effects of the calcium antagonist nitrendipine and the diuretic hydrochlorothiazide on plasma calciotropic hormone concentrations and lumbar bone density were compared during the treatment of hypertension in a randomized, double-blind, 8 week parallel study, followed by a 52 week open label study. There were 32 subjects with stable essential hypertension (sitting diastolic blood pressure ≥95 mm Hg and ≤115 mm Hg without medication) without evidence of renal insufficiency or active heart disease. They were randomly assigned to receive either 10 mg nitrendipine twice daily or 50 mg hydrochlorothiazide daily. In order to reach and maintain target blood pressure (diastolic blood pressure ≤95 mm Hg) during the open label period, the nitrendipine dose was titrated up to 30 mg twice daily, and additional antihypertensive drugs, of differing classes, were added as necessary. Blood samples were analyzed for concentrations of calcium, parathyroid hormone, and calcitonin, and lumbar bone density was determined by dual photon absorptiometry, at the baseline and at 24 and 52 weeks of antihypertensive drug therapy. Nitrendipine increased serum calcium (baseline 9.6 ± 0.3 to 9.9 ± 0.5 mg/dL, P ≤ .05) and parathyroid hormone concentrations (baseline 32.5 ± 10.0 to 39.7 ± 14.6 μLEq/mL, P ≤ .05) at 24 weeks and reduced calcitonin at both 24 and 52 weeks (from 16.8 ± 10.5 pg/mL at baseline to 7.9 ± 6.1 pg/mL and 10.4 ± 6.9 pg/mL, respectively, both P ≤ .01); hydrochlorothiazide increased serum calcium at 24 and 52 weeks and did not change parathyroid hormone, and reduced calcitonin at 24 weeks (baseline 15.7 ± 6.0 pg/mL to 10.1 ± 5.4 pg/mL, P ≤ .05). Nitrendipine did not alter bone density, whereas hydrochlorothiazide increased bone density at both 24 and 52 weeks (from 1.177 ± 0.164 g/cm2 at baseline to 1.243 ± 0.173 g/cm2 and 1.248 ± 0.166 g/cm2, respectively, P ≤ .05). Antihypertensive treatment with nitrendipine for 52 weeks does not alter lumbar bone density, but does decrease plasma calcitonin while increasing serum calcium. This modulation of calciotropic hormone concentrations may participate in the mechanism of blood pressure reduction. Am J Hypertens 1992;5:875-879