Utility of alpha subunit determination after thyrotropin-releasing hormone stimulation as an indicator of gonadotropinoma persistence and/or recurrence.

OBJECTIVE: Gonadotropinomas are adenomas of the gonadotropic cells of the anterior pituitary. These cells produce and secrete gonadotropins (follicle-stimulating hormone and luteinizing hormone). Most of these tumors show altered production of gonadotropins and their subunits (the p-FSH, a and, less frequently, p-LH subunits). The thyrotropin-releasing hormone (TRH) stimulation test could differentiate these tumors from nonfunctioning tumors. Equally, this test could be able to distinguish between postsurgical changes and tumoral remnants after surgery. SUBJECTS AND METHOD: We studied 24 patients with pituitary macroadenoma, 14 of who had a histological diagnosis of gonadotroph adenoma. The TRH stimulation test was performed before and after surgery. RESULTS: Both before and after surgery, a positive result to the TRH test was obtained in 50% of gonadotropinomas. Magnetic resonance imaging (MRI) performed after surgery revealed that 83% of the patients with gonadotropinoma had signs of tumoral persistence or recurrence and/or postsurgical changes. Of these patients, 83% (41.6% of the total) showed positive a subunit stimulation after the TRH test. In the group of non-gonadotropinoma macroadenomas, only 33% had a positive result before surgery and another 33% had a positive result after surgery. In the MRI performed after surgery, all showed tumoral persistence/recurrence or postsurgical inflammatory changes. CONCLUSIONS: This test could be useful in the differential diagnosis of gonadotropinomas as well as in the follow-upand postsurgical evaluation of these tumors.