Which patients with gynaecomastia require more detailed investigation?

Gynaecomastia may be due to medication, chronic liver or kidney disease, hypogonadism (primary or secondary to pituitary disease) or hyperthyroidism. Having excluded these aetiologies, it is imperative to be vigilant for underlying malignancy causing gynaecomastia. These include human chorionic gonadotrophin-secreting testicular and extratesticular tumours and oestrogen-secreting testicular tumours and feminising adrenal tumours.