• Enlargement of breast tissue in men
  • Not uncommon (more common than reported)- may occur in up to 30% of men
  • Incidence increases with age; but also very common feature in neonates due to placental transfer of maternal hormones
  • Causes may be physiological or pathological


  • Physiological
    • Trimodal age distribution
      • Neonatal
      • Adolescents (around 50% of males will experience gynaecomastia at 13/14 due to increase in oestrogen and testosterone hormones)
        • Often resolves spontaneously but can be psychologically distressing
      • Old age (decreasing free testosterone)
  • Non-physiological
    • Persistent adolescent symptoms
    • Obesity (fat is a store for oestrogen and can cause gynaecomastia)
    • Medications
      • Anti-androgenic e.g. chemotherapy agents; isoniazid; ketoconazole; methotrexate; metronidazole; omeprazole; ranitidine; spironolactone; penicillamine, cimetidine
      • Oestrogenic properties e.g. Anabolic steroids; diazepam; digoxin; oestrogens; phenytoin
      • Increased metabolism of androgens e.g. Alcohol
      • Increased sex hormone binding globulin e.g. diazepam, phenytoin
      • Induces hyperprolactinaemia e.g. Haloperidol and antipsychotics; metoclopramide
      • Unknown e.g. amiodarone; amlodipine and other CCBs; ACEIs; antiretrovirals; atorvastatin; diltiazem; fluoxetine and other SSRIs/antidepressants; heroin/methadone
    • Pathology
      • Cirrhosis/Liver disease
      • Primary Hypogonadism
      • Tumours e.g. Leydig (oestrogen producing) testicular cancer; adrenal tumours
      • Hyperthyroidism
      • Chronic Kidney Disease
      • Cushing’s


  • Onset, duration and timing
  • Associated pain/tenderness
  • Associated symptoms- particularly ask about sexual dysfunction/impotence; also ask about others and explore alternative diagnoses where appropriate
  • Ask about PMHx and RHx; social Hx including alcohol, illicit drug use and smoking


  • Examine the tissue- is it true breast tissue or adipose (fat- pseudogynaecomastia)
    • True gynaecomastia can be felt as a separate tissue mass under the skin
    • Size/symmetry
  • Look for any evidence of chronic liver disease or kidney disease
  • Look also for any signs of hyperthyroidism or Cushing’s
  • Look at the testes for any signs of atrophy, tumour or cryptorchidism


  • USS may help differentiate adipose and breast tissue if uncertain
  • If an underlying medication or other cause is not found (e.g. liver failure, kidney failure, hyperthyroidism etc), then
    • Testosterone
    • LH, FSH, oestrodiol, prolactin and hCG (tumour marker)
      • If LH high and testosterone low- may indicate testicular failure
      • If LH and testosterone both low- usually due to increase in oestrogens
      • If LH and testosterone both high- androgen resistance or neoplasm secreting gonadotrophin

NB An underlying cause is often not found

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