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Reduction in Intestinal Calcium Absorption by Hydrochlorothiazide in Postmenopausal Osteoporosis*

1984; Oxford University Press; Volume: 59; Issue: 6 Linguagem: Inglês

10.1210/jcem-59-6-1037

1945-7197

Khashayar Sakhaee, Michael J. Nicar, Kenneth Glass, Joseph E. Zerwekh, Charles Y.C. Pak,

Parathyroid Disorders and Treatments

In six women with postmenopausal osteoporosis, most of whom responded to 50 μg/day 25-hydroxyvitamin D (25-OHD) therapy with a rise in intestinal calcium (Ca) absorption, 50 mg/day hydrochlorothiazide (TZ) were added to determine whether the resulting decline in urinary Ca would cause Ca retention in the skeleton. Urinary Ca decreased from 183 ± 48 (SD) mg/day to 142 ± 67 mg/day (P < 0.05) when TZ was added. However, fractional Ca absorption also declined from 0.532 ± 0.077 during 25-OHD treatment to 0.401 ± 0.064 during combined 25-OHD and TZ therapy (P < 0.0025). The above changes were accompanied by a significant decline in urinary cAMP from 4.29 ± 1.64 to 3.19 ± 1.44 μmol/g creatinine (P < 0.05) and in serum 1,25-dihydroxyvitamin D from 41 ± 14 to 22 ± 11 pg/ml (P < 0.01). The results suggest that TZ lowers urinary Ca, suppresses parathyroid function, inhibits 1,25-dihydroxyvitamin D synthesis, and thereby reduces intestinal Ca absorption. Thus, combined 25-OHD and TZ therapy probably does not improve Ca balance.