Response of plasma endorphins, corticotropin, cortisol, and luteinizing hormone in the corticotropin-releasing hormone stimulation test in eumenorrheic and amenorrheic athletes.

We compared pituitary response in the corticotropin-releasing hormone (CRH) test between 9 eumenorrheic and 10 amenorrheic endurance athletes. The maximal oxygen capacity (VO2max), determined using an exercise test on a bicycle ergometer, was larger in amenorrheic (62.7 +/- 1.0 SE mL/min per kg) than in eumenorrheic (54.7 +/- 2.3 mL/min per kg) athletes. A 100 micrograms bolus of human CRH was administered intravenously, and blood samples were collected at -15, 0, 30, 60, 90, and 120 minutes. The mean basal concentrations of endorphins, adrenocorticotropic hormone (ACTH), and cortisol did not show significant differences between the groups. The cumulative response of ACTH in the CRH test was larger in eumenorrheic (7.7 +/- 1.3 pmol/L) than in amenorrheic (3.6 +/- 0.6 pmol/L) athletes, but the response of endorphins and cortisol did not differ between the groups. A negative correlation was found between the VO2max and the ACTH response during the CRH test in the total group of athletes. These findings indicated changes in the function of hypothalamic-pituitary-adrenal axis in amenorrheic athletes that can be attributed to intensive training.