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.