BIOCHEMICAL SHORT-TERM CHANGES PRODUCED BY HORMONAL REPLACEMENT THERAPY

Seventy-one white women within 6 months to 6 years postmenopause were randomly assigned to three treatment groups: (a) placebo, (b) calcium, (c) cyclic estrogen-progestin plus calcium. Calcium was given as calcium carbonate with meals to attain an intake of 1,700 mg daily in the latter two groups. All women received 400 IU of vitamin D daily. Samples were obtained at baseline and after 2 months therapy. The hormonal treatment group had a decline in serum calcium, osteocalcin and urinary hydroxyproline and an increase in levels of calcitonin, parathyroid hormone and calcitriol. The increase in the latter two measurements could have resulted from the drop in serum calcium, it is also possible that the increase in calcitonin levels was a result of calcium supplementation. Although all these changes were statistically significant for the estrogen treatment group when considered alone, analysis of variance including the 3 groups demonstrated significance for the estrogen group for the parameters of skeletal metabolism but not for the changes in the calciotrophic hormones. There was an increase in serum calcium (p = 0.05) in the calcium augmentation group. It would be of interest to determine the effects of higher intakes of calcium in both the calcium and the estrogen treatment groups and to further explore differences in effects on bone remodeling between the two treatment approaches as well as the possibility of a additive effects. Early effects of estrogen replacement reduce bone remodeling whereas calcium supplementation to 1,700 mg per day of Ca CO3 did not appear to affect the parameters of bone remodeling.