Euprolactinemic Galactorrhea. Response of bioassayable prolactin to thyrotropin-releasing hormone.

OBJECTIVE

To define whether the pathophysiology of euprolactinemic galactorrhea (EuG) involves hyperresponsiveness to thyrotropin-releasing hormone (TRH).

STUDY DESIGN

Basal and TRH-induced prolactin (PRL) patterns were examined in women with EuG (n = 7) and compared to those in controls (n = 10) with normal menstrual cycles. PRL activity was measured by radioimmunoassay (RIA) and Nb2 lymphoma cell bioassay (BA). The response of BA-PRL, RIA-PRL, the BA/RIA-PRL ratio and lactogenic activity to TRH given intravenously were studied.

RESULTS

The response of RIA-PRL, BA-PRL, lactogenic activity (representing both PRL and growth hormone in the Nb2 lymphoma cell bioassay) and BA/RIA-PRL ratio were not significantly different in EuG as compared to controls. In both groups the combined BA/ RIA-PRL ratio increased at 15 (P = .006), 30 (P = .011), and 90 minutes (P = .022) after TRH injection as compared to zero time. The level of serum progesterone at the time of TRH stimulation did not affect the response of any parameter studied.

CONCLUSION

The response of BA-PRL, RIA-PRL and the BA/RIA-PRL ratio to TRH was not significantly different in EuG as compared to controls. The mechanism of EuG did not involve hyperresponsiveness of BA-PRL, RIA-PRL, the BA/RIA-PRL ratio or lactogenic activity to TRH.