Hormonal Causes of Gynecomastia — When to Investigate

Not every gynecomastia requires a hormonal workup. Longstanding stable gynecomastia in an otherwise healthy adult man rarely reveals an underlying endocrine disorder. But some presentations — recent onset, rapid progression, unilateral disease, tenderness, a palpable distinct mass, or unusual patient profiles — mandate investigation before surgery. Missing an underlying pituitary adenoma, hypogonadism, liver disease, or rare malignancy is a clinical error surgery cannot correct.

Physiological causes (no workup required)

• Neonatal gynecomastia — transient, from maternal oestrogens; resolves in weeks
• Pubertal gynecomastia — onset age 10–14, typically resolves within 18 months without intervention. Persistent gynecomastia beyond age 20 warrants investigation
• Senescent gynecomastia — after age 60, physiological testosterone decline and adipose aromatisation drive the condition. Workup only if atypical features present

Pathological causes warranting investigation

Primary hypogonadism

Testicular failure (Klinefelter syndrome, mumps orchitis, trauma, chemotherapy, varicocele) — low testosterone with compensatory elevated LH/FSH. Klinefelter syndrome (47,XXY) is the most important to identify because it carries a significantly elevated breast cancer risk (20-50× the general male population) — affecting long-term surveillance strategy.

Secondary hypogonadism

Pituitary or hypothalamic dysfunction — low testosterone with inappropriately normal or low LH/FSH. Causes include prolactinoma (prolactin-secreting pituitary tumour), non-functioning pituitary adenoma, Kallmann syndrome, or severe systemic illness.

Hyperthyroidism

Increases sex-hormone-binding globulin (SHBG), lowering free testosterone relative to estradiol. Gynecomastia may be the presenting feature. Thyroid function tests (TSH, free T4) are part of the standard workup.

Chronic liver disease

Impaired hepatic clearance of oestrogens and androgen-binding proteins produces an altered testosterone-to-oestrogen ratio. Alcoholism, NAFLD, hepatitis, and cirrhosis all contribute. Spironolactone (often used in cirrhosis for ascites) compounds the issue pharmacologically.

Renal failure / chronic dialysis

Uraemia suppresses testosterone production and alters sex steroid metabolism. Gynecomastia in dialysis patients is common.

Tumours — rare but must not be missed

• Testicular tumours — Leydig cell, Sertoli cell, or germ cell (β-hCG secreting). Warrants testicular examination at consultation; ultrasound if any mass or asymmetry
• Adrenal tumours — estrogen-secreting carcinoma. Rare. Elevated estradiol with suppressed LH/FSH
• Extragonadal germ cell tumours — mediastinal or retroperitoneal, secreting hCG. Elevated hCG points here
• Lung carcinoma — ectopic hCG secretion from paraneoplastic lung cancer. Rare but classically presents with gynecomastia as a paraneoplastic sign

These are uncommon but their detection at the pre-operative workup stage, rather than after years of misdiagnosis, is the entire point of hormonal screening.

Drug-induced gynecomastia

The most common cause of drug-induced gynecomastia in routine clinical populations (excluding anabolic steroids, covered separately):

When to order a hormonal panel — indications

1. Onset within the last 6 months — active proliferation phase, workup can reveal a reversible cause
2. Rapid progression over weeks rather than months
3. Significant tenderness or pain — inflammatory / active phase
4. Unilateral presentation — raises differential of neoplasm
5. Persistent pubertal gynecomastia beyond age 20
6. Systemic symptoms — weight loss, fatigue, visual disturbances, headaches, testicular pain or swelling
7. Palpable hard or fixed mass distinct from the normal glandular disc — mandates imaging and possibly biopsy before surgery
8. Abnormal testicular examination — testis examination is mandatory at gynecomastia consultation
9. Family history of breast cancer in male relatives, BRCA, or Klinefelter

The standard hormonal panel

• Total testosterone (morning sample) and free testosterone (if indicated)
• LH and FSH — to localise the hypogonadism (primary vs. secondary)
• Estradiol — measured directly (not calculated)
• Prolactin — elevated in prolactinoma, some drug effects
• β-hCG — elevated in germ cell tumours, hCG-secreting malignancy
• TSH, free T4 — thyroid function
• Liver function tests — ALT, AST, albumin, bilirubin
• Renal function — creatinine, eGFR
• SHBG (selectively) — to calculate bioavailable testosterone

Imaging when indicated

• Breast ultrasound — for unilateral presentation, discrete hard mass, or equivocal examination
• Mammography — rarely needed in typical male gynecomastia but indicated if ultrasound suggests malignancy or patient is elderly with new unilateral disease
• Testicular ultrasound — for abnormal examination, tenderness, or elevated hCG
• Pituitary MRI — for confirmed hyperprolactinaemia or features suggesting pituitary dysfunction