The neuroendocrine response of luteinizing hormone to estrogen administration in the human is not sex specific but dependent on the hormonal environment.

Mammals are known to have a sex-specific response of LH secretion to sequential estrogen administration. Females respond with an increase in LH secretion, while males have a decrease. This study of genetic male and genetic female transsexual subjects was done to determine if this sexual differentiation of the LH response to estrogen exposure applies to the human. All subjects were tested before hormone therapy while in the eugonadal state corresponding to their genetic sex and again during cross-gender hormone therapy subsequent to gonadectomy. Transsexuals of both genetic sexes had a LH response to estrogen administration appropriate to their genetic sex before gonadectomy and hormone therapy. The same individuals had the opposite response, appropriate to their reassigned sex, after gonadectomy and while receiving cross-gender hormone therapy. I conclude that the LH response to an estrogen stimulus is not sex specific in humans and is not irrevocably designated perinatally. Psychoneuroendocrine studies linking homosexuality and transsexualism to the type of LH response to estrogen administration should be viewed in the light of these results.