Rapid suppression of S-PTH by oral calcitriol and calcium in healthy premenopausal women.

摘要

The influence of oral calcium +/- cholecalciferol or calcitriol on S-PTH and whole blood ionized calcium (B-Ca++) in the very short term has not been elucidated. B-Ca++ and S-PTH were measured after overnight fast every 5 or 15 min for 4-h in 7 healthy premenopausal women (30-45 years) in a crossover design where the subjects were studied on 4 different days. Study 1: (control), 125-ml tap water (also given in studies 2-4); study 2: 1000 mg calcium, as calcium carbonate; study 3: 1000 mg calcium and 400 IU (5 microg) cholecalciferol; and study 4: 0.5 microg calcitriol plus 1000 mg calcium. Calcium plus 1,25(OH)2 vitamin D3 induced a rapid and significant fall in S-PTH compared to the control period (p < 0.02). Calcium alone or calcium plus cholecalciferol did not change the PTH levels significantly compared to control (water). B-Ca++ increased significantly after calcium plus 1,25(OH)2 vitamin D3 (p<0.01) and calcium plus cholecalciferol (pZ0.05) compared to the control period. The B-Ca++ elevation was significantly higher after calcium plus 1,25 vitamin D3 than after calcium plus cholecalciferol (p?.05). In conclusion, oral calcitriol plus calcium causes a rapid elevation in B-Ca++ and suppression of the PTH secretion also in the short term (hours).