Hypothyroidism with presenting symptoms of fibrositis.

Eight patients who initially presented with signs and symptoms of the fibrositis syndrome, without overt hypothyroid disease, were found to have chemical evidence of hypothyroidism. Myalgic symptoms resolved in 6 of 8 patients treated with low dose thyroid replacement. In addition, another hypothesis of pathophysiology of the myalgic symptoms observed in patients with hypothyroidism related to sleep disturbance is offered.