COMBINED BETA-FSH AND BETA-LH RESPONSE TO TRH IN PATIENTS WITH CLINICALLY NONFUNCTIONING PITUITARY-ADENOMAS

OBJECTIVE 'Paradoxical' responses of LH, FSH, alpha-subunits and beta LH to TRH have previously been reported in individuals with clinically non-functioning pituitary tumours (NFT), The present study was design ed to assess the in vivo and in vitro responses of beta FSH to TRH in NFT. We further examined the possibility that a TRH challenge with com bined measurement of beta FSH and beta LH will identify a common anoma lous secretory pattern in patients with NFT, DESIGN, PATIENTS AND MEAS UREMENTS Forty patients with NFT underwent a standard TRH test (400 mu g intravenously), Blood samples for the determination of beta FSH, be ta LH, FSH and LH were collected prior to TRH as well as 15, 30, 45, 6 0 and 90 minutes following injection, Additionally, cultured adenomato us cells from eight of these patients were exposed to TRH in the absen ce and presence of octreotide and gonadotropin subunits were determine d, RESULTS TRH elicited a marked rise in circulating beta FSH in 29 of 40 individuals and in beta LH in 28 of 36 patients with NFT. In a sub group of eight individuals whose tumours were harvested during surgery and cultured for 7-21 days, TRH increased beta FSH or beta LH and alp ha-subunit release in cultured adenomatous cells in all cases, includi ng tumours from subjects not responding to TRH in vivo. In this subgro up of patients octreotide inhibited basal beta FSH secretion but not b asal beta LH secretion both in vivo and in primary cultures of NFT cel ls, Both the in vivo and in vitro beta FSH, beta LH and alpha-subunit responses to TRH were entirely inhibited by octreotide. In all, 38 of the 40 subjects could be identified by either elevated basal beta FSH or beta LH levels and/or an abnormal rise in either beta FSH or beta L H in response to TRH.CONCLUSION The measurement of basal and TRH-stimu lated beta-FSH and beta-LH levels identifies an abnormal hormonal secr etory pattern in the vast majority (>90%) of patients with clinically nonfunctioning pituitary tumours.