Background: Gynecomastia had been developed infrequently in male patients with hyperthyroidism as a result of the increase in the physiologically active estrogen to androgen ratio. However, its occurrence as the initial presentation in patients with undiagnosed hyperthyroidism is extremely uncommon. We report an unusual case of hyperthyroid Graves’ disease presented with unilateral gynecomastia.
Clinical Case: A 24-year-old Thai man complained of non-painful enlargement of left breast with palpitation, excessive sweating and weight loss 3 kilograms in 1 month. Physical examination revealed non-tender, palpable glandular tissues, measuring about 3 cm beneath and around left areola. Moderately diffuse thyroid goiter with bruit was also found. He had no obvious thyroid-associated eye signs. Hyperthyroidism Graves’ disease was confirmed biochemically with highly elevated anti-TSH receptor antibody. Further laboratory investigations showed an elevated serum estradiol of 88 pg/ml (normal range in male 10-40 pg/ml) and highly elevated serum total testosterone at > 15 ng/ml (normal range in male 2.5-8.4 pg/ml). Treatment of hyperthyroidism with methimazole resulted in resolution of the gynecomastia within 2 months and patient was received radioiodine treatment as a definitive treatment for Graves’ disease.
Conclusion: Although the association of gynecomastia and hyperthyroidism was described for more than one century, the frequency and severity of this manifestation vary widely among affected patients, and in rare cases gynecomastia could be an initial presentation of hyperthyroidism in male patients. The balance between free testosterone and estrogen in patients with hyperthyroidism is affected by elevated serum levels of sex hormone binding globulin. The clinical manifestations of hyperthyroidism are multi-system, mainly caused by the acceleration of various physiological processes in all organs. This case highlights the importance of considering hyperthyroidism in male patients presented with unilateral gynecomastia.