Gynecomastia as the initial manifestation of hyperthyroidism

To present two new cases of gynecomastia as the initial manifestation of hyperthyroidism. We describe detailed case reports of two men with breast enlargement who were found to have hyperthyroidism, and we review the related literature. Two men sought medical assistance because of unilateral tender gynecomastia. In one of these patients, thyroid, gonadal, and prostate examinations showed normal findings at the time of initial assessment, and symptoms of hyperthyroidism developed later. In our other patient with gynecomastia, other symptoms of hyperthyroidism--for example, nervousness, irritability, palpitations, and fatigue--had been present for a prolonged period but had been considered "normal" by the patient. In both patients, the hyperthyroidism was treated with radioiodine. Breast pain disappeared in both patients, and breast enlargement disappeared in one patient and was decreased in the other patient after euthyroidism was achieved. Review of the literature disclosed only two similar cases. Because of the rarity of gynecomastia as the initial symptom of hyperthyroidism, we believe that thyroid function tests are not indicated in the workup of patients whose major complaint is gynecomastia.