The effect of thyrotropin-releasing hormone on gonadotropin and free alpha-subunit secretion in patients with acromegaly and functionless pituitary tumors.
Paradoxical response of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and alpha-subunits (alpha-SU) to thyrotropin-releasing hormone (TRH) have previously been reported in individuals with clinically nonfunctioning pituitary tumors (NFT). In the present study, we assessed the in vivo responses of LH, FSH, alpha-SU to TRH in 34 patients with NFT and 29 patients with agromegaly. Twenty-three clinically NFT were postoperatively analyzed by immunocytochemistry and 21 stained positive for beta-FSH and/or beta-LH. Two patients with NFT had elevated basal circulating levels of FSH (41.5 IU/L) and thus were characterized as FSH-secreting adenomas. TRH in these patients increased LH from basal 1.6 IU/L to 32.6 IU/L. In other patients with NFT, circulating levels of glycoprotein peptides were not elevated. TRH induced significant rise of LH in 8 (23.5%), FSH in 5 (14.7%), and alpha-SU in 10 (29.4%) patients with NFT. Thus, a bolus dose of TRH elicited a notable increment in FSH, LH or alpha-SU in 23 of 34 patients with NFT. Among 29 patients with acromegaly, LH rose in 6 (20.7%), FSH in 5 (17.2%), and alpha-SU in 3 (10.3%) patients.


CONCLUSIONS
(1) We confirm that most NFTs are capable of synthesizing gonadotropin hormones and subunits (beta-FSH, beta-LH). (2) Most patients in our study responded by either FSH, LH or alpha-SU secretion after TRH, independent of basal hormone levels. Furthermore, recent studies show that by measurement of TRH stimulated beta-FSH and beta-LH one might further improve the diagnostic tools. (3) Gonadotropin response and possibly alpha-SU to TRH are also found in some patients with acromegaly. This could be a marker of a plurihormonal pituitary tumor.
Popovic
V
V
Institute of Endocrinology, University Clinical Center, Belgrade, Yugoslavia.
Damjanovic
S
S
D000172:Acromegaly / Q000097:blood*; D000236:Adenoma / Q000097:blood* / Q000378:metabolism; D000293:Adolescent; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal; D002064:Buserelin / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood*; D006065:Gonadotropins, Pituitary / Q000097:blood*; D006801:Humans; D007150:Immunohistochemistry; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000097:blood* / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D018931:Antineoplastic Agents, Hormonal; D015292:Glycoprotein Hormones, alpha Subunit; D006065:Gonadotropins, Pituitary; D013973:Thyrotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D002064:Buserelin