Improvement of spermatogenesis after treatment with the antiestrogen tamoxifen in a man with the incomplete androgen insensitivity syndrome

Abstract

A 32-yr-old man with a history of hypospadias, unilateral cryptorchidism, and pubertal gynecomastia (all surgically corrected) presented with complaints of infertility. Examination revealed scant virilization, recurrence of gynecomastia, small but normal sized testes, small prostate, and oligospermia. His plasma LH, testosterone, dihydrotestosterone, and estradiol levels were high, and his plasma FSH was below the reference range of adult men. An assay of pubic skin fibroblast androgen receptors confirmed the diagnosis of a form of incomplete androgen insensitivity syndrome. Administration of the estrogen receptor antagonist tamoxifen (10 mg, twice daily) induced an increase in plasma FSH greater than that which occurred in six men with idiopathic oligospermia. This man’s wife conceived three times during a period of 5 yr, each time after he had received tamoxifen for 12–20 weeks and had considerable improvement of sperm parameters. Conversely, upon cessation of tamoxifen therapy, the semen abnormalities returned. These results indicate that estrogen action impaired this man’s fertility, and the impairment could be reversed by administration of an estrogen receptor antagonist. © 1989 by The Endocrine Society.