Fibromyalgia:

Abstract

Objectives: Previous studies have suggested an association between fibromyalgia [FS] and thyroid dysfunction. This assocation was explored in this prospective case-control study. Methods: One-hundred and eight females with FS and 72 female controls were studied. Patients on medicatons which interfere with the interpretation of thyroid testing were excluded. Fibromyalgia was diagnosed by a brief history and physical examination using the criteria established by the American College of Rheumatology [ACR]. Thyroid stimulation hormone [TSH], L-thyroxine [T4], 3,5,3'-triiodo-L-thyronine uptake [T3], and T7 [T3U × T4] were determined for each subject. Results: Females with FS reported a history of thyroid disorder [hypothyroidism, hyperthyroidism] 2.5 times more frequently than control subjects [P < 0.05]. Hypothyroidism was the most common diagnosis. The T3U levels were significantly lower in the FS group than in thecontrols [P = 0.02]. Three times as many fibromyalgics had one or more abnormal tests on the thyroid panel as compared to controls, but that difference was not statistically significant. A composite measure of thyroid dysfunction [history of thyroid abnormality plus newly diagnosed thyroid abnormality] indicated a 2.5 fold higher risk among fibromyalgics [P < 0.05]. A significantly higher age-adjusted prevalence of six symptoms associated with thyroid dysfunction in patients with FS [P < 0.01] was found. Conclusions: Females with FS reported a history of hypothyroidism or hyperthyroidism more frequently than did females in the control group. Symptoms commonly associated with thyroid dysfunction were reported by fibromyalgics more often than by controls. The data indicates, however, that these symptoms are not specific and a diagnosis of thyroid disease should be made only with confirmatory laboratory tests.

KEYWORDS:

• Fibromyalgia
• Thyroid dysfunction
• Hypothyroidism