Prevention of post-menopausal bone loss with 1 alpha-hydroxy vitamin D3. A three-year prospective study.

An open and controlled prospective study was used to assess the preventive efficiency of 1 alpha-hydroxy vitamin D3 (1 alpha (OH) Vit. D3) on post-menopausal vertebral bone loss. Of the 36 patients included in the study, 25 completed two years of treatment with 1 microgram/day of 1 alpha (OH) Vit. D3 and 500 mg of calcium. The vertebral bone mineral density measured by dual photon absorptiometry did not vary in the treated group, whereas it decreased significantly in the control group at the end of the 2 years. At two years, withdrawal of treatment led to a significant bone loss, whereas bone mass remained stable in a subgroup of patients who underwent a third year of treatment with 1 alpha (OH) Vit. D3. Overall, tolerance was satisfactory. However, urinary calcium increased significantly during treatment and one third of the patients developed hypercalciuria > or = 7.5 mmoles/24 h. No variation in either serum calcium or creatinine levels was noted. These results indicate that 1 alpha (OH) Vit. D3 could be useful in preventing post-menopausal bone loss provided it was complemented by regular monitoring of urinary calcium excretion.