Urinary Free Cortisol Excetion in Chronic Fatigue Syndrome

A recent study compared the urinary free cortisol excretion (UFC) in 21 patients with chronic fatigue syndrome (CFS), in 10 melancholic depressives and in 15 healthy controls.

CFS patients had significantly lower UFC excretion than the healthy comparison group, whereas patients with depression had UFC values which were significantly higher than healthy comparison subjects.

These findings are in keeping with currently held hypotheses of hyperactivity and hypoactivity of the hypothalamic-pituitary-adrenal (HPA) axis in both depression and chronic fatigue syndrome.

Five of the 21 CFS patients had a co-morbid depressive illness. This sub-group retained the profile of UFC excretion of those with CFS alone, suggesting a different pathophysiological basis for depressive symptoms in CFS.

(Journal of Affective Disorders [1998], 47[1-3]: 49-54)