Prolactin Response to Metoclopramide and Chlorpromazine in Primary Testicular Failure and Isolated Gonadotrophin Deficiency

The aim of the present study was to measure the PRL response to metoclopramide (MET) and chlorpromazine (CPZ) in seventeen patients with primary testicular failure and eight patients with isolated gonadotrophin deficiency (IGD). The responses were compared with those to TRH. Basal gonadotrophins and peak responses to LHRH were increased in testicular failure and reduced in IGD. Basal PRL levels were normal in both groups of patients. However, when compared with controls, the PRL response to both MET and CPZ as well as to TRH was exaggerated in primary testicular failure, whereas the responses wee decreased in IGD. In both patient groups, as well as in the controls, the PRL response to MET exceeded that to TRH and CPZ. It is suggested that alterations in the steroid milieu are responsible for the exaggerated PRL response to MET, CPZ and TRH in primary testicular failure and the reduced response observed in IGD.