Fibromyalgia-Like Syndrome Secondary to Addison's Disease

Fibromyalgia is a syndrome of musculoskeletal pain and tenderness in specific sites, fatigue, and sleep disturbance. Fibromyalgia may occur in patients with rheumatoid arthritis and other connective tissue diseases. Despite the fact that fibromyalgia patients may have alterations in the hypothalamic-pituitary-adrenal axis, no relationship had been established between fibromyalgia and diseases of the adrenal cortex. We report a case of a 46-year-old woman who presented with a new onset of a fibromyalgia-like syndrome meeting all American College of Rheumatology criteria except chronicity. Additional clinical features, including skin pigmentation, mild hypertension, and hyponatremia, as well as further laboratory testing led to a diagnosis of autoimmune Addison's disease. After steroid replacement, the symptoms of fibromyalgia disappeared. This is the first case in English-language literature of fibromyalgia secondary to Addison's disease. We suggest Addison's disease should be considered in the differential diagnosis of any patient with a fibromyalgia-like syndrome.