Endocrine Abstracts

Introduction: Gynecomastia is a benign excessive proliferation of glandular tissue in the male breast and results from an increased breast estrogen/androgen activity ratio. It may be physiological (infancy, puberty or aging) or pathological. The most common cause is drug-induced. Although hyperthyroidism is a rare cause(1.5%), gynecomastia occurs in up to 25-40% of males with Graves’ disease and is often undiagnosed. Its development as the first manifestation of this thyroid disease is quite unusual. We present a case of a young man with gynecomastia as a presenting sign of Graves’ disease.

Case report: 34-years-old male with chronic kidney disease (reflux nephropathy) since childhood, arterial hypertension and hyperuricemia, treated with lercanidipine, alopurinol and sodium bicarbonate, was referred to Endocrinology appointment due to a nonpainful increase in breast volume, right breast tension for 1 year, mild hyperprolactinemia and a newly diagnosed thyrotoxicosis. Clinically, he referred a recent slight hands’ tremor at rest and notion of bilateral periorbital edema for 2 weeks. He denied galactorrhoea, headaches, visual disturbances, symptoms of hypogonadism, drug or steroid consumption as well as other thyroid function disruptors, previous testicular surgery, radiation or trauma. Physical examination: bilateral nonpainful gynecomastia, inversion of left nipple, bilateral exophthalmos, resting tremor, BP 153/1 mmHg, HR 107-117 bpm. Blood workup: TSH<0.01 uUI/ml (0.38-5.33), FT3 5.91 pg/ml (2.5-4.4), FT4 2.1 ng/dl (0.54-1.24), TRAbs 8.1 UI/l (<2.9), prolactin 36.8 ng/ml (2.6-13.1), LH 9.8 mUI/ml (1.2-8.6), FSH 8mUI/ml (1.3-19.3), total testosterone 5.1 ng/ml (1.98-6.79), estradiol 32 pg/ml (<30), SHBG 73.5 nmol/l (13-71), beta-hCG 0.5 mUI/ml (<2.7), alpha-fetoprotein 1.1 ng/ml (<9). Thyroid ultrasound:normal volume, hypoechogenic heterogenous structure, no nodules. Breast ultrasound:asymmetric gynecomastia (more pronounced on the right) and 1 mm left retro-areolar cyst. Scrotal ultrasound:mild asymmetry in testicular dimension, homogenous structure, regular margins, no nodules. Diagnosis:hyperthyroidism due to Graves’ disease and hyperprolactinemia likely due to chronic kidney disease. Treatment:methimazole (MMI)1 mg/day. At 2 months follow-up, thyroid function tests were TSH <0.01uUI/ml, FT4 1.1 ng/dl (normal), FT3 3.74 pg/ml (normal), allowing for slow reduction in MMI.

Discussion and Conclusions: In this patient, possible causes of gynecomastia were chronic kidney disease, hyperprolactinemia and hyperthyroidism. However, due to long-standing kidney disease with no documented recent worsening of their baseline function, a very slight elevation of prolactin and recent development of gynecomastia and symptoms of hyperthyroidism, the most likely cause is the latter. Hyperthyroidism induces gynecomastia through a combination of decreased free androgen levels and overproduction of estrogens. It is important that clinicians perform thyroid function tests when evaluating a patient with gynecomastia, even when other possible causes coexist, so that the diagnosis and treatment of hyperthyroidism are not missed.