Can Graves disease cause gynecomastia in males?

Can Graves Disease Cause Gynecomastia?

Yes, Graves disease can definitely cause gynecomastia in males, though it is an uncommon presenting symptom. 1, 2, 3, 4

Mechanism and Prevalence

Hyperthyroidism from Graves disease causes gynecomastia through hormonal imbalances—specifically through increased sex hormone-binding globulin (SHBG) and altered estrogen-to-androgen ratios. 3, 5

• Gynecomastia occurs in 30-40% of men with Graves hyperthyroidism, though it rarely presents as the initial or predominant symptom. 3
• The condition results from deficient androgen action or excessive estrogen action in breast tissue, which occurs in hyperthyroid states. 5
• Hyperthyroidism should be considered as an underlying hormonal disorder when evaluating any patient with gynecomastia. 1

Clinical Presentation Patterns

Gynecomastia from Graves disease can present either unilaterally or bilaterally:

• Bilateral progressive gynecomastia is the typical presentation pattern. 2
• Unilateral gynecomastia can occasionally occur as the presenting manifestation, though this is less common. 2, 4
• The breast tissue may be tender and painful, particularly in acute presentations. 2, 3, 4

Diagnostic Approach

When a male patient presents with gynecomastia, thyroid function testing should be part of the initial hormonal workup:

• Measure serum TSH and free T4 to screen for thyrotoxicosis. 2, 4
• If hyperthyroidism is confirmed, measure anti-TSH receptor antibodies to confirm Graves disease. 2
• The American Urological Association recommends referring men with elevated baseline estradiol measurements to an endocrinologist to determine the underlying hormonal cause. 6
• Assess for other signs of thyrotoxicosis including weight loss, palpitations, heat intolerance, tremors, and thyroid enlargement with bruit. 2, 4

Treatment and Resolution

Complete resolution of gynecomastia can be achieved within a few months after thyrotoxicosis is resolved in patients with recent-onset gynecomastia:

• Treatment with anti-thyroid medication normalizes thyroid hormone, sex hormones, and SHBG levels, leading to resolution of gynecomastia. 3
• Radioiodine ablation (RAI) is recommended for definitive treatment in young adults with very high anti-TSH receptor antibody levels and severe thyrotoxicosis. 2
• Complete resolution without recurrence typically occurs within 3 months of achieving euthyroid status. 2
• For men with hypogonadism contributing to gynecomastia, androgen administration might be helpful after thyroid function is normalized. 5

Important Clinical Pitfalls

• Patients with unexplained gynecomastia or breast masses should always be screened for thyrotoxicosis, as hyperthyroid states may present deceptively with single organ system involvement. 4
• Gynecomastia as the sole presenting symptom of Graves disease is uncommon and can distract from the correct diagnosis. 3, 4
• Failing to assess for underlying medical conditions such as thyroid disease is a common pitfall in gynecomastia evaluation. 1
• Most men with breast symptoms can be diagnosed clinically without imaging, but if differentiation from breast cancer cannot be made clinically, proceed with appropriate imaging based on age. 6, 7