Integrity of the growth hormone/insulin-like growth factor system is maintained in patients with chronic fatigue syndrome

GH deficiency states and chronic fatigue syndrome (CFS) share several chara cteristics, and preliminary studies have revealed aspects of GH dysfunction in CFS. This study assessed indexes of GH function in 37 medication-free C FS patients without comorbid psychiatric illness and 37 matched healthy con trols. We also assessed GH function before and after treatment with low dos e hydrocortisone, which has been shown recently to reduce fatigue in CFS. W e measured basal levels of serum insulin-like growth factor I (IGF-I), IGF- II, IGF-binding protein-1 (IGFBP-1), IGFBP-2 and IGFBP-3 together with 24-h urinary GH excretion. We also performed 2 dynamic tests of GH function: a 100-mu g GHRH test and an insulin stress test using 0.15 U/kgBW insulin. Th ere were no differences between patients and controls in basal levels of IG F/IGFBP or in urinary GH excretion. GH responses to both the GHRH test and the insulin stress test were no different in patients and controls. CFS pat ients did have a marginally reduced suppression of IGFBP-1 during the insul in stress test. Hydrocortisone treatment had no significant effect on any o f these parameters. There is no evidence of GH deficiency in CFS. At the do ses used, hydrocortisone treatment appears to have little impact on GH func tion.