EFFECTS OF POSTMENOPAUSAL HORMONE REPLACEMENT THERAPY WITH AND WITHOUT VITAMIN-D-3 ON CIRCULATING LEVELS OF 25-HYDROXYVITAMIN-D AND 1,25-DIHYDROXYVITAMIN-D
Am. Heikkinen et al., EFFECTS OF POSTMENOPAUSAL HORMONE REPLACEMENT THERAPY WITH AND WITHOUT VITAMIN-D-3 ON CIRCULATING LEVELS OF 25-HYDROXYVITAMIN-D AND 1,25-DIHYDROXYVITAMIN-D, Calcified tissue international, 62(1), 1998, pp. 26-30
The effects of postmenopausal hormone replacement therapy (HRT) and vi
tamin D-3 on vitamin D metabolites (25OHD and 1,25(OH)(2)D) were studi
ed in a population-based prospective 1-year study. The serum concentra
tions of intact parathyroid hormone (PTH), calcium, and phosphate were
also studied. A total of 72 women were randomized into four treatment
groups: HRT group (sequential combination of 2 mg estradiol valerate
and 1 mg cyproterone acetate), Vir D-3 group (vitamin D-3 300 IU/day calcium lactate 500 mg/day), HRT + Vit D-3 group (both above) and pla
cebo group (calcium lactate 500 mg/day). Serum samples were taken in M
arch-Api-il when vitamin D formation from sunlight in Finland is minim
al after the dark winter, Serum concentrations of 25OHD increased in t
he Vit D-3 group (33.5%, P < 0.001) and in the HRT + Vit D-3 group (38
.2%, P < 0.001) but had not changed significantly in the HRT and place
bo groups at the I-year follow-up examination. Serum concentrations of
calcitriol (1,25(OH)(2)D) increased, however, only in the HRT group (
23.7%, P < 0.05), and remained unchanged in other groups. Serum concen
trations of PTH decreased by 23.2% (P < 0.05) in the placebo group, bu
t did not change significantly in the other three groups. The concentr
ations of serum calcium increased in the nonhormone groups (P < 0.001)
, whereas serum phosphate concentrations decreased in the hormone grou
ps (P < 0.05 and 0.001), Our results confirm the positive effect of 1
year of HRT an serum calcitriol, Vitamin D-3 supplementation increased
25OHD concentrations, bur did not affect calcitriol concentrations ev
en though the initial levels were low, Interestingly, the combination
of HRT and vitamin D-3 did not increase serum calcitriol concentration
s as much as HRT alone.