Effect of transdermal 17 beta-estradiol and oral conjugated equine estrogens on biochemical parameters of bone resorption in natural menopause.

OBJECTIVE

To evaluate and compare the effects or oral and transdermal estrogen replacement therapy on biochemical markers of bone resorption in early postmenopausal women.

DESIGN

Controlled, randomized group comparison.

SETTING

Outpatient clinic for menopausal women and research into osteoporosis.

SUBJECTS

Sixty healthy women menopausal for less than 5 years and who had never received any medications interfering with bone metabolism.

INTERVENTIONS

The 60 women were randomly allocated to 3 months therapy with either oral conjugated estrogens (0.625 mg/day) (n = 28) or transdermal estradiol (50 micrograms/day) (n = 32) in cyclical combination with medroxyprogesterone acetate (5 mg/day).

MAIN OUTCOME MEASURES

Traditional (urinary calcium/creatinine and hydroxyproline/creatinine) and the new specific (urinary pyridinoline/creatinine and deoxypyridinoline/creatinine) markers of bone resorption were determined before and after 3 months of treatment.

RESULTS

In both groups, circulating levels of estrone and estradiol were significantly (P < 0.001) increased during treatment. In women treated with oral conjugated equine estrogens, urinary calcium/creatinine and hydroxyproline/creatinine ratios were significantly (P < 0.05) reduced. Pyridinoline/creatinine ratio fell from 69.1 (4) [mean (SEM)] to 50 (4) mumol/mumol (P < 0.01) and deoxypyridinoline/creatinine ratio fell from 10.8 (1) [mean (SEM)] to 8.3 (0.8) mumol/mumol (P < 0.01). In the group treated with transdermal estradiol, urinary hydroxyproline/creatinine ratio was significantly (P < 0.05) reduced. Pyridinoline/creatinine ratio fell from 66.3 (4) [mean (SEM)] to 46.2 (3) mumol/mumol (P < 0.01) and deoxypyridinoline/creatinine ratio fell from 11.5 (1.5) [mean (SEM)] to 7.7 (0.6) mumol/mumol (P < 0.01). There were no differences between the evolution of the biochemical variables in the two groups.

CONCLUSION

These results suggest that oral conjugated equine estrogens and transdermal estradiol, in the given doses, are equally effective in reducing postmenopausal bone resorption.