Bulimia nervosa--a primary defect in the hypothalamic-pituitary-adrenal axis?

Bulimia nervosa has been associated with impaired satiety, decreased resting metabolic rate and abnormal neuroendocrine regulation. The aim of this study was to investigate the diurnal cortisol secretion and the pituitary-adrenal response to corticotropin-releasing hormone (CRH) in subjects suffering from bulimia nervosa. Eight female subjects with remitted bulimia nervosa, ages 24-56, and 8 sex- and weight-matched controls volunteered to participate. After an overnight fast they were admitted to the Clinical Research Center for 24 hour recording of plasma cortisol secretion. Blood were drawn every 2nd hour from 8 AM. After another overnight fast, the subjects performed a 120-min CRH test (100 microg i.v.), drawn for measurements of adrenocorticotropin releasing hormone (ACTH) and cortisol. Compared to the control group (CG), the diurnal cortisol secretions in the bulimic group (BG) decreased at time points 6 AM to 2 PM. In the CRH test, the ACTH response was significantly stronger in the BG than in the CG. Similar observations were found for cortisol, although not at significant levels. Remitted bulimic patients exhibit a neuroendocrine pattern of decreased HPA axis activity with a hyperreactivity to CRH. This may indicate a complex and so far poorly understood neuroendocrine dysregulation of HPA axis associated with the disease.