Abstract
Tamoxifen (TAM), a non steroid partially competitive antagonist to the estrogen receptors, has been reported to decrease plasma GH and IGF-I levels both in vitro and in vivo. These data prompted us to evaluate GH and IGF-I changes in acromegaly after acute and chronic TAM administration. Nineteen acromegalic patients (6 M, 13 F, aged 30–70 years) were studied in a prospective open study. Acute TAM test (20 mg po) did not induce any significant change in GH and IGF-I levels. Chronic TAM treatment (20 mg/day for a month and 40 mg/day for another month) induced a transient increase in GH levels (from 9 [3–139] µg/l [median, range] to 12 [3-188] µg/l, p=0.0025) and a persistent decrease in IGF-I levels (from 785 [500-1200] µg/l to 553 [209-1420] µg/l, p=0.0034). Individual IGF-I values decreased in 13 patients and reached the normal range in 4 of them. At TAM withdrawal hormonal levels increased up to pretreatment values. There was no correlation between GH and IGF-I changes and results were not influenced by age, sex or gonadal status. In this setting it is likely that the observed decrease in plasma IGF-I levels is dependent on TAM activity at the hepatic level.
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Cozzi, R., Attanasio, R., Oppizzi, G. et al. Effects of tamoxifen on GH and IGF-I levels in acromegaly. J Endocrinol Invest 20, 445–451 (1997). https://doi.org/10.1007/BF03348000
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DOI: https://doi.org/10.1007/BF03348000