Effects of tamoxifen on the levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin (PRL), 17 beta-oestradiol (E2), total and free testosterone (T) and total and free dihydrotestosterone (DHT) in blood of patients with benign prostatic hyperplasia.

: Treatment of 9 patients with benign prostatic hyperplasia with 20 mg tamoxifen daily for 6 weeks resulted in a significant increase of LH (211%), FSH (215%), E2 (231%), total T (157%), free T (148%) and total DHT (148%) levels in blood. The increase of plasma free DHT (152%) levels was not significant and PRL concentrations in serum were unchanged during treatment. Comparison of the increases between total T and free T, total T and total DHT as well as free T and free DHT failed to reveal any significant differences. These results imply (1) a marked anti-oestrogenic effect of tamoxifen at the level of hypothalamo-hypophysial axis (2) no effect at the hepatic oestrogen receptor sites indicated by unchanged SHBG-bound T and DHT in plasma and (3) no significant inhibitory effect of tamoxifen on 5 alpha-reductase activity concluded from the T/DHT ratio in peripheral circulation. In view of these findings tamoxifen appears to be unsuitable for therapy of benign prostatic hyperplasia.