Abnormalities in Parathyroid Hormone Secretion and 1,25-Dihydroxyvitamin D3Formation in Women with Osteoporosis

Abstract
We investigated the parathyroid hormone–1,25-dihydroxyvitamin D3 (1,25(OH)2D) axis in osteoporosis by administering phosphate to 8 postmenopausal women with osteoporosis (49 to 78 years old) and to 10 normal women matched for age (50 to 74 years). All subjects responded with a similar increase in the serum phosphorus concentration (women with osteoporosis, 1.15±0.06 to 1.79±0.09 mmol per liter; controls, 1.14±0.05 to 1.73±0.08 mmol per liter) and a fall in the ionized calcium concentration (women with osteoporosis, 1.12±0.03 to 1.06±0.03 mmol per liter; controls, 1.17±0.01 to 1.11 ±0.02 mmol per liter).