Effect of conventional and newer forms of treatment on calcium absorption in osteoporosis.

Studies carried out in this Research Unit and by others have shown that patients with osteoporosis absorb less calcium from a high calcium intake than do patients without osteoporosis. To determine whether various treatment modalities would increase the intestinal absorption of calcium, the effects of conventional and new methods were investigated. Tracer doses of 47Ca were given orally to determine the absorption of calcium. Calcium balances were also determined. Estrogen decreased urinary calcium and testosterone increased the nitrogen balance. Vitamin D and strontium increased the urinary calcium but did not increase calcium absorption. Of the newer compounds, fluoride did not affect calcium absorption but decreased urinary calcium. Phosphate had a similar effect. Infusions containing up to 15 mg calcium/kg, given for 6 or 10 days, increased the retention of calcium but did not increase its absorption.