Pituitary function before, during, and after chronic gonadotropin-releasing hormone agonist therapy.

Objective: To examine possible adverse effects on pituitary function of long-term administration of gonadotropin-releasing hormone agonist (GnRH-a).
Design: Prospective analysis of blood sampling before, during, and after GnRH-a therapy.
Setting: Tertiary institutional outpatient care.
Patients: Twelve normally ovulatory women with a diagnosis of endometriosis.
Interventions: Six-month suppression with GnRH-a.
Main Outcome Measures: Serum levels of follicle-stimulating hormone, luteinizing hormone, free thyroxin index, cortisol (F), growth hormone (GH), prolactin (PRL), and thyroid-stimulating hormone (TSH).
Results: Basal and stimulated values of gonadotropins, PRL, F, TSH, and GH were normal and unchanged by 6 months of GnRH-a after resumption of menses.
Conclusions: Utilizing dynamic pituitary function tests, we were unable to demonstrate an adverse effect of long-term GnRH-a therapy on pituitary function.