Elevated basal levels and exaggerated responses to thyrotrophin-releasing hormone of prolactin and thyrotrophin in Turner-Noonan-Syndrome.

Basal levels of prolactin (Prl), FSH, LH, testosterone, estradiol, total thyroxine (T4), total triiodothyronine (T3) and thyrotrophin (TSH) were determined in four males with Turner-Noonan-Syndrome. The responsiveness of gonadotrophins to LH-RH (100 micrograms i.v.) and of Prl and TSH (200 micrograms i.v.) was studied. High basal levels and exaggerated responses to TRH of Prl were found in all patients. However no evidence of any of the well known causes of hyperprolactinaemia could be detected in them. The four men were with normal levels of T4 and T3 and showed exaggerated TSH responses to TRH. It is suggested that the alterations in Prl and TSH release are reflections of a congenital disorder in Turner-Noonan-Syndrome not yet well studied.