Effect of transdermal l7?-estradiol and oral conjugated equine estrogens on biochemical parameters of bone resorption in natural menopause

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Abstract
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 jig/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) μmol/μmol (P < 0.01) and deoxypyridinoline/creatinine ratio fell from 10.8 (1) [mean (SEM)] to 8.3 (0.8) μmol/μmol (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) μmol/μmol (P < 0.01) and deoxypyridinoline/creatinine ratio fell from 11.5 (1.5) [mean (SEM)] to 7.7 (0.6) μmol/μmol (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.