Combined βFSH and βLH response to TRH in patients with clinically non- functioning pituitary adenomas

D. Somjen, K. Tordjman, F. Kohen, M. Baz, N. Razon, G. Ouaknine, N. Stern

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: 'Paradoxical' responses of LH, FSH, α-subunits and βLH to TRH have previously been reported in individuals with clinically non- functioning pituitary tumours (NFT). The present study was designed to assess the in vivo and in vitro responses of βFSH to TRH in NFT. We further examined the possibility that a TRH challenge with combined measurement of βFSH and βLH will identify a common anomalous secretory pattern in patients with NFT. DESIGN, PATIENTS AND MEASUREMENTS: Forty patients with NFT underwent a standard TRH test (400 μg intravenously). Blood samples for the determination of βFSH, βLH, FSH and LH were collected prior to TRH as well as 15, 30, 45, 60 and 90 minutes following injection. Additionally, cultured adenomatous cells from eight of these patients were exposed to TRH in the absence and presence of octreotide and gonadotropin subunits were determined. RESULTS: TRH elicited a marked rise in circulating βFSH in 29 of 40 individuals and in βLH in 28 of 36 patients with NFT. In a subgroup of eight individuals whose tumours were harvested during surgery and cultured for 7- 21 days, TRH increased βFSH or βLH and α-subunit release in cultured adenomatous cells in all cases, including tumours from subjects not responding to TRH in vivo. In this subgroup of patients octreotide inhibited basal βFSH secretion but not basal βLH secretion both in vivo and in primary cultures of NFT cells. Both the in vivo and in vitro βFSH, βLH and α-subunit responses to TRH were entirely inhibited by octreotide. In all, 38 of the 40 subjects could be identified by either elevated basal βFSH or βLH levels and/or an abnormal rise in either βFSH or βLH in response to TRH. CONCLUSION: The measurement of basal and TRH-stimulated β-FSH and β-LH levels identifies an abnormal hormonal secretory pattern in the vast majority (>90%) of patients with clinically nonfunctioning pituitary tumours.

Original languageEnglish
Pages (from-to)555-562
Number of pages8
JournalClinical Endocrinology
Volume46
Issue number5
DOIs
StatePublished - 1997

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