Oral administration of estrogen replacement therapy suppresses the biological actions of growth hormones in GH-defic...( d Ken K. Y. Ho all from The Garvan Ins...)

d Ken K. Y. Ho, all from The Garvan Institute of Medical Research, St. Vincent's Hospital and Biomedical Mass Spectrometry Unit, University of New South Wales, Sydney, Australia; and Mark W. Duncan and Margot Umpleby, both from The Endocrine and Diabetic Unit, St. Thomas's Hospital, London.

Protocols

Ten hypopituitary GH-deficient women with hypogonadism were recruited from the Endocrine Outpatient Clinic at St. Vincent's Hospital (Sydney, Australia). They were randomized into two separate studies, which were separated by at least three months. Six subjects participated in both studies. Growth hormone deficiency was confirmed by a peak GH response of <3 ng/ml during an insulin tolerance test. The duration of hypopituitarism was at least one year, and no subjects had received GH before. All hypopituitary subjects were receiving stable hormone replacement for other deficiencies, except for one subject of postmenopausal age who did not receive sex steroid replacement.

Study Design

Eight subjects participated in each study. Both studies were of open-label, randomized, crossover design, allowing for differences in treatment effect (i.e., route of estrogen administration) to be compared during estrogen therapy. Each subject was randomized to 2 mg/day oral estradiol valerate or transdermal estrogen patches delivering 100 g of 17estradiol daily for eight weeks. The subjects then crossed over to the alternate estrogen treatment for an additional eight weeks. The estrogen dosages used were based on data indicating equivalent biological activity, as measured by gonadotropin suppression and vaginal cytology. Medroxyprogesterone acetate (10 mg daily) was coadministered on the last 12 days of each four-week cycle of estrogen treatment to induce withdrawal bleeding.

The Dose-Response Study

The growth hormone Genotropin was administered in a stepwise incremental regimen during the second month of each estrogen phase, at a dose of 0.
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Contact: Donna Krupa
djkrupa1@aol.com
703-527-7357
American Physiological Society
30-Nov-2001

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