Prospective evaluation of thyroid function in patients with systemic sclerosis (scleroderma).

A consecutive series of 77 ambulatory, clinically euthyroid patients with systemic sclerosis was evaluated for clinical, chemical and serologic evidence of thyroid disease. Measurements of baseline serum thyroid function tests and the thyroid stimulating hormone response to thyrotropin releasing hormone (TRH) were made. We classified 18 (23%) patients as abnormal, including 8 (10%) who were chemically hypothyroid and 10 (13%) with normal baseline studies but an exaggerated response to TRH injection. The remaining 59 (77%) patients were euthyroid by all measurements. Antithyroid antibodies were present in only 4 of 8 (50%) of the hypothyroid group. There were no differences between the 3 patient groups with regard to the extent of scleroderma, the presence of internal organ involvement, or the frequency of common signs or symptoms of hypothyroidism. Abnormal thyroid function in systemic sclerosis is frequent, often unsuspected clinically, and may occur without markers of autoimmune thyroid disease.