Hypothalamic-pituitary-gonadal axis and cortisol in young women with primary fibromyalgia: the potential roles of depression, fatigue, and sleep disturbance in the occurrence of hypocortisolism

OBJECTIVES: To investigate abnormalities of the hypothalamic-pituitary-gonadal (HPG) axis and cortisol concentrations in young women with primary fibromyalgia (FM); and to determine whether depression, fatigue, and sleep disturbance affect these hormones. METHODS: Follicle stimulating hormone (FSH), luteinising hormone (LH), oestradiol, progesterone, prolactin, and cortisol concentrations in 63 women with FM were compared with those in 38 matched healthy controls; all subjects aged <35 years. The depression rate was assessed by the Beck Depression Inventory (BDI) and patients with high and low BDI scores were compared. Additionally, patients were divided according to sleep disturbance and fatigue and compared both with healthy controls and within the group. RESULTS: No significant differences in FSH, LH, oestradiol, prolactin, and progesterone levels were found between patients with FM and controls, but cortisol levels were significantly lower in patients than in controls (p<0.05). Cortisol levels in patients with high BDI scores, fatigue, and sleep disturbance were significantly lower than in controls (p<0.05). Correlation between cortisol levels and number of tender points in all patients was significant (r = -0.32, p<0.05). CONCLUSION: Despite low cortisol concentrations in young women with FM, there is no abnormality in HPG axis hormones. Because fatigue, depression rate, sleep disturbance, and mean age of patients affect cortisol levels, these variables should be taken into account in future investigations.