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Endocrine Abstracts (2024) 99 EP198 | DOI: 10.1530/endoabs.99.EP198

ECE2024 Eposter Presentations Thyroid (198 abstracts)

Gynecomastia as the first manifestation of thyrotoxicosis: an unusual case report

Catarina Cidade-Rodrigues 1 , Vania Benido Silva 1 , Bruna Silva 1 & Margarida Almeida 1


1Centro Hospitalar do Tamega e Sousa, Endocrinology, Penafiel, Portugal


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.

Volume 99

26th European Congress of Endocrinology

Stockholm, Sweden
11 May 2024 - 14 May 2024

European Society of Endocrinology 

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