The effects of sodium fluoride, calcium phosphate, and vitamin D 2 for one to two years on calcium and phosphorus metabolism in postmenopausal women with spinal crush fracture osteoporosis

Abstract

Calcium and phosphorus balances and 47Ca turnover studies were performed before and after 12–27 months of daily treatment with sodium fluoride (60 mg), calcium (30–45 mmol), phosphate (29–44 mmol), and vitamin D 2 (18,000 IU) in 20 postmenopausal women with spinal crush fracture osteoporosis. Before treatment the mean calcium balance (−1.6 mmol Ca/day) was negative ( P < 0.05), whereas the mean phosphorus balance ( −1.6 mmol P day ) did not differ from zero( P > 0.10). The treatment induced an increase in calcium absorption ( P < 0.01) with an unchanged renal excretion and dermal loss of calcium and an increase ( P < 0.02) in calcium balance, which became positive ( P < 0.01) ( + 3.3 mmol Ca day ). This enhancement in calcium balance was obtained by the combined effects of an increase ( P < 0.05) in bone mineralization rate and a decrease ( P < 0.05) in bone resorption rate. The observed increase in net phosphorus absorption ( P < 0.001) was more pronounced than the increase in renal excretion of phosphorus ( P < 0.001), and the phosphorus balance therefore increased ( P < 0.001) and became positive ( P < 0.001). A positive correlation was observed between net calcium and net phosphorus absorption ( r = 0.065; P < 0.001) in the 32 studies where both calcium and phosphorus balance data were available. Furthermore, a positive correlation ( r = 0.61; P < 0.05) was found between the changes in net calcium and net phosphorus absorption during treatment. The results indicate that the combined treatment with sodium fluoride, calcium, phosphate, and vitamin D 2 induces a positive calcium and phosphorus balance in postmenopausal women with osteoporosis.