Gail K. Adler, M.D., Ph.D.

Many of the symptoms of fibromyalgia – fatigue, pain, disrupted sleep, orthostatic symptoms, reduced exercise tolerance, and impaired cognitive function – resemble those of patients suffering from hormone deficiencies. In particular, many of these symptoms are experienced by patients with reduced functioning of the hypothalamic-pituitary-adrenocortical axis, growth hormone-IGF-1 axis, and sympathoadrenal system. Studies on the functioning of these hormone systems in individuals with fibromyalgia have tended to show impairment in a significant number of individuals. However, the role of neuroendocrine dysfunction in the pathophysiology of fibromyalgia is unclear. It is likely these hormone deficiencies contribute to the maintenance of the fibromyalgia syndrome, and possibly to the initial development of the syndrome.

It is unclear why multiple hormone abnormalities are observed. This may suggest that there are multiple etiologies for fibromyalgia. It is also possible that deficiencies in one hormone system lead to abnormalities in another. For example, there is a positive feedback loop between hypothalamic corticotropin-releasing hormone (CRH) and the sympathetic nervous system. Thus, a primary defect in one system may lead to reduced function in the other. CRH gene expression is also influenced by factors whose regulation has been postulated to be abnormal in fibromyalgia: serotonin, neuropeptide Y, substance P. Finally, CRH, glucocortiocoids, catecholamines, and serotonin alter regulation of the growth hormone-IGF-1 axis. Therefore, it may be appropriate to think of these hormone systems, not in isolation, but as dynamic, interacting systems. 

Presented at the National Fibromyalgia Research Association's New Dimensions in Fibromyalgia Symposium, September 14-15, 1997, in Portland, Oregon.