Is there an association between fibromyalgia and below-normal levels of urinary cortisol?

BACKGROUND: Adynamia in fibromyalgia (FM) may be an expression of a functional deficit of the hypothalamic-pituitary-adrenal axis and be associated with below-normal levels of urinary cortisol. Our aim was to demonstrate that urinary cortisol was lower in patients with FM than in healthy subjects. FINDINGS: We measured urinary cortisol levels for a sample of 47 women aged 29 to 64 years (mean age 53 years), diagnosed with FM 2–3 years previously, and compared the results with those for a control sample of 58 healthy women of a similar age. Samples of 24-hour urine were appropriately collected and levels of urinary cortisol were measured using the fluorescence polarization immunoassay method. The mean cortisol value for the women with FM was 65.40 ± 27.10 μg/L, significantly lower than the mean cortisol level for the control group, at 90.83 ± 38.17 μg/L (p < 0.001). CONCLUSION: Our study confirms that women with FM have significantly lower urinary cortisol levels than healthy women.