Unlabelled

In this clinical trial of 12.5 or 25 mg/day of hydrochlorothiazide, the urine calcium showed significant decreases from placebo in men at one year, but the effects had waned by 3 years. Serum bicarbonate was consistently greater in the thiazide than in the placebo groups throughout the three years. These effects could be beneficial to the skeleton.

Introduction

Previous studies have shown increased bone density and reduced risk of fracture in patients taking thiazide diuretics. The long-term effects of low-dose thiazides on mineral metabolism have not been reported in normal subjects.

Methods

We conducted a randomized, double-blinded trial in normals aged 60-79 years, using hydrochlorothiazide 12.5 or 25 mg/d or placebo for three years. Subjects were encouraged to maintain calcium intake of 1,000 to 1,500 mg/day. Measurements of serum and urine calcium metabolism were done at baseline, six months, and yearly. Data were analyzed in 88 men and 177 women who had taken study medication. Adjusted change in the measurements from baseline to one and three years were compared among groups.

Results

The calcium intake increased in all groups. Urine calcium per day was significantly lower in thiazide than placebo groups in men at one year but not at three years; in women the changes were not significantly different. Serum bicarbonate was higher in thiazide compared to placebo groups at one and three years. No changes were seen in serum calcium, phosphate, parathyroid hormone, sodium or magnesium.

Conclusions

The results suggest that both increased calcium availability from a hypocalciuric effect and reduction in acid-induced bone buffering could be mechanisms for the beneficial skeletal effects.

The purpose of this study was to compare biochemical markers of bone resorption and formation in young women using different hormonal contraceptive methods. Women aged 18-39 yr who were using depot medroxyprogesterone acetate (DMPA) contraception were recruited for the study; comparison women were matched by age and clinic location. There were 116 women using DMPA, 39 using oral contraceptives containing estrogen and progestin, and 72 not currently using hormonal contraceptives. Biochemical measurements were serum calcium, PTH and osteocalcin, and urine N-telopeptide. Bone density was measured using dual-energy x-ray absorptiometry. The N-telopeptide levels, adjusted for age and other risk factors, were 42.4 +/- 2.3 nmol/mmol creatinine in the DMPA group, 26.2 +/- 3.3 nmol/mmol in the oral contraceptive group, and 35.4 +/- 2.9 nmol/mmol in the nonusers; significant differences were seen in all pairwise comparisons. Osteocalcin levels showed the same pattern, although the difference between the DMPA users and nonusers was not statistically significant. There were no differences among groups in the PTH levels. The bone density at the spine was 1.086 +/- 0.085 g/cm(2) in the DMPA group, 1.103 +/- 0.095 g/cm(2) in the oral contraceptive group, and 1.093 +/- 0.090 g/cm(2) in nonusers (P = 0.051). The results suggest that in women using DMPA bone resorption exceeded bone formation.