The effects of sodium fluoride, calcium phosphate, and vitamin D2 for one to two years on calcium and phosphorus metabolism in postmenopausal women with spinal crush fracture osteoporosis.

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 D2 (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 less than 0.05), whereas the mean phosphorus balance (-1.6 mmol P/day) did not differ from zero (P greater than 0.10). The treatment induced an increase in calcium absorption (P less than 0.01) with an unchanged renal excretion and dermal loss of calcium and an increase (P less than 0.02) in calcium balance, which became positive (P less than 0.01) (+3.3 mmol Ca/day). This enhancement in calcium balance was obtained by the combined effects of an increase (P less than 0.05) in bone mineralization rate and a decrease (P less than 0.05) in bone resorption rate. The observed increase in net phosphorus absorption (P less than 0.001) was more pronounced than the increase in renal excretion of phosphorus (P less than 0.001), and the phosphorus balance therefore increased (P less than 0.001) and became positive (P less than 0.001). A positive correlation was observed between net calcium and net phosphorus absorption (r = 0.065; (P less than 0.001) in the 32 studies where both calcium and phosphorus balance data were available. Furthermore, a positive correlation (r = 0.61; P less than 0.05) was found between the changes in net calcium and net phosphorus absorption during treatment.(ABSTRACT TRUNCATED AT 250 WORDS)