Pituitary release of growth hormone and prolactin in the primary fibromyalgia syndrome.

OBJECTIVE

Previously, we demonstrated hyperreactive adrenocorticotropic hormone (ACTH) release in patients with primary fibromyalgia syndrome (primary FMS). We investigated the pituitary release of growth hormone (GH) and prolactin (PRL) in search of further disturbances in neuroendocrine reactivity possibly associated with the pathophysiology of primary FMS.

METHODS

Ten female patients with primary FMS fulfilling the 1981 Yunus criteria and 10 matched, healthy and sedentary controls were subjected to an insulin induced hypoglycemia test; samples for measurement of glucose, GH and PRL were taken at intervals.

RESULTS

Compared to the controls, the patients with primary FMS displayed significantly lower basal GH levels, whereas their basal PRL levels were slightly, though significantly, higher (respectively p = 0.021 and p = 0.041). Following hypoglycemia, there was a marked, statistically highly significant (p = 0.001), hyperreactivity of the GH response in patients with primary FMS. The PRL response showed wide interindividual variation and did not differ between patients and controls.

CONCLUSION

Our findings indicate that fibromyalgia, along with ACTH hyperreactivity, also exhibits a distinct disturbance in the GH-somatomedin C axis. With regard to PRL, the variation in individual responses limits conclusions. The hyperreactive response patterns of GH and ACTH previously suggest a common origin, which might be related to a subtle glucocorticoid deficiency.