Some chronic pain conditions and comorbidities suppress the hypothalamic-pituitary-adrenal (HPA) axis and response to dynamic testing. We measured HPA axis responses to corticotropin-releasing hormone (CRH) administration in relation to chronic pelvic pain and endometriosis. In a cross-sectional study of women (n = 54) with endometriosis-associated chronic pelvic pain (n = 22), chronic pelvic pain alone (n = 12), or healthy volunteers (n = 20), adrenocorticotropic-releasing hormone (ACTH) and cortisol levels were measured at 0, 15, 30, and 45 min after intravenous ovine CRH administration. ACTH and cortisol delta (peak-baseline) and area under the curve (AUC) were compared by study group and assessed for association with race and menstrual and non-menstrual pain severity. HPA axis responses did not differ among the racially diverse groups or in those with pain compared with healthy volunteers. However, when stratified by race, ACTH delta (129.9 ± 130.7 vs. 52.5 ± 66.0 pg/mL; p = 0.003), ACTH AUC (4813 ± 4707 vs. 2290 ± 2900 min*pg/mL; p = 0.013), and cortisol delta (26.3 ± 21.5 vs. 13.2 ± 9.7 μg/mL; p = 0.005) were significantly higher in black (n = 10) than predominately white (non-black) subjects (n = 44; 39/44 white). In analyses among primarily white (non-black) women, greater menstrual pain severity was associated with blunted ACTH delta (p = 0.015) and cortisol delta (p = 0.023), and greater non-menstrual pain severity with blunted cortisol delta (p = 0.017). Neuroendocrine abnormalities in women with chronic pelvic pain may differ by pain manifestations and may vary by race. The higher HPA axis response in black women merits investigation in pelvic pain studies stratified by race. In white (non-black) women experiencing pain, a blunted response was related to pain severity suggesting pain affects women independently of endometriosis lesions.
Keywords: ACTH; CRH stimulation; Chronic pelvic pain; Cortisol; Endometriosis; HPA axis response.