Background. The prevalence of thyroid disease in patients with alopecia areata previously reported varied from 0 to 28%. These thyroid diseases include Hashimoto's thyroiditis. Graves' disease, simple goiter, and others.

Methods. The prevalence of thyroid diseases was determined in 152 consecutive patients with alopecia areata who presented to the dermatology clinic. A complete history was taken and a physical examination was performed. Thyroxine, triiodothyronine, thyroid-stimulating hormone, and microsomal antibody levels were measured in every patient. The control group consisted of 152 age- and sex-matched volunteers who had skin diseases other than alopecia areata or autoimmune disorders.

Results. Among 152 patients, age 10–59 years, four cases (2.6%) had a small simple goiter. Microsomal antibodies were detected in seven other patients (4.6%) with liters ranging from 1:100 to 1:1600. None of these seven patients had signs or symptoms of thyroid disease. Five cases (3.3%) of the control group had positive microsomal antibody tests with titers ranging from 1:100 to 1:400. The prevalence of positive microsomal antibodies in the alopecia areata group was not statistically different from the control group (x2= 0.347, df= 1, P = 0.5558).

Conclusions. Among 152 patients with alopecia areata, 4.6% of patients had microsomal antibodies and 2.6% had a small simple goiter. Thus the prevalence of thyroid disease among these patients was 7.2%. The prevalence of positive microsomal antibodies in 4.6% of the patients was not statistically different from that of the control group.