Functioning of the hypothalamic-pituitary-adrenal and growth hormone axes in frequently unexplained disorders: Results of a population study

Abstract

Background The aim of the study was to test the hypothesis that associations with specific stress systems [hypothalamic-pituitary-adrenal (HPA) and growth hormone (GH) axes] would increase as the number of unexplained disorders increased while accounting for the possible confounding effects of psychosocial factors. Methods A cross-sectional study identified those reporting chronic widespread pain, irritable bowel syndrome, chronic orofacial pain and chronic fatigue. Of the 1315 subjects, disorder status was available for 1180 (89.7%), of whom 766 (64.9%) reported no disorders, 277 (23.5%) reported one and 137 (11.6%) reported two or more. Eighty subjects were sought from each group for assessment of HPA (morning 8:00 a.m. and evening 10:00 p.m. saliva, and post-dexamethasone serum cortisol levels) and GH [serum insulin-like growth factor 1 (IGF-1) level] axis function. Validated questionnaires informed current psychological state. Results Two hundred twenty-seven subjects participated [79 (35%) with no disorders, 78 (34%) with one disorder and 70 (31%) with two or more disorders]. There were no significant associations (p-