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Causes
By Mayo Clinic staff
Gynecomastia is triggered by a decrease in the amount of the hormone testosterone compared with estrogen. The cause of this decrease can be conditions that block the effects of or reduce testosterone or by a condition that increases your estrogen level. Several things can upset the hormone balance, including:
- Natural hormone changes
- Medications
- Certain health conditions
In about 25 percent of cases, the cause of gynecomastia is never found.
The testosterone-estrogen balance
The hormones testosterone and estrogen control the development and maintenance of sex characteristics in both men and women. Testosterone controls male traits such as muscle mass and body hair; estrogen controls female traits including the growth of breasts.
Most people think of estrogen as an exclusively female hormone, but men also produce it — though normally in small quantities. Estrogen helps regulate bone density, sperm production and mood. But male estrogen levels that are too high or are out of balance with testosterone levels can cause gynecomastia.
Gynecomastia in infants
More than half of male infants are born with enlarged breasts due to the effects of their mother's estrogen. Generally the swollen breast tissue goes away within two to three weeks after birth.
Gynecomastia during puberty
Gynecomastia caused by hormone changes during puberty is common. In most cases, the swollen breast tissue will go away without treatment within six months to two or three years.
Gynecomastia in men
The prevalence of gynecomastia peaks again between the ages of 50 and 80. At least one-quarter of men are affected during this time.
Medications
A number of medications can cause gynecomastia. These include certain:
- Anti-androgens used to treat prostate enlargement or cancer and some other conditions. Examples include cyproterone, flutamide, finasteride and spironolactone.
- AIDS medications. Gynecomastia can develop in HIV-positive men who are receiving a treatment regimen called highly active antiretroviral therapy (HAART). Efavirenz is more commonly associated with gynecomastia than are other HIV medications.
- Anti-anxiety medications, such as diazepam (Valium).
- Tricyclic antidepressants.
- Antibiotics.
- Ulcer medications, such as cimetidine.
- Cancer treatment (chemotherapy).
- Heart medications, such as digitalis and calcium channel blockers.
Street drugs and alcohol
Substances that can cause gynecomastia include:
- Anabolic steroids and androgens
- Alcohol
- Amphetamines
- Marijuana
- Heroin
Health conditions
Several health conditions can cause gynecomastia by affecting the normal balance of hormones. These include:
- Hypogonadism. Any of the conditions that interfere with normal testosterone production, such as Klinefelter syndrome or pituitary insufficiency, can be associated with gynecomastia.
- Aging. Hormone changes that occur with normal aging can cause gynecomastia, especially in men who are overweight.
- Tumors. Some tumors, such as those involving the testes, adrenal glands or pituitary gland, can produce hormones that alter the male-female hormone balance.
- Hyperthyroidism. In this condition, the thyroid gland produces too much of the hormone thyroxine.
- Kidney failure.
- Liver failure and cirrhosis.
- Malnutrition and starvation.
Herbal products
Plant oils, such as tea tree or lavender, used in shampoos, soaps or lotions, have been associated with gynecomastia. This is probably due to their weak estrogenic activity.
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- Braunstein GD. Causes and evaluation of gynecomastia. http://www.uptodate.com/home/index.html. Accessed Sept. 17, 2008.
- Braunstein GD. Management of gynecomastia. http://www.uptodate.com/home/index.html. Accessed Sept. 17, 2008.
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- Testicular Disorders. In: Kronenberg HM, et al. Williams Textbook of Endocrinology. 11th ed. St. Louis, Mo. Saunders Elsevier; 2008. http://www.mdconsult.com/das/book/body/111383897-2/0/1555/0.html. Accessed Nov. 24, 2008.
- Fitzgerald PA. Gynecomastia. In: McPhee SJ et al. CURRENT Medical Diagnosis & Treatment. 48th ed. San Francisco, Calif.: The McGraw-Hill Companies; 2009. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=1. Accessed Nov. 24, 2008.
- Shalender B. Disorders of the Testes and Male Reproductive System. In: Fauci AS, et al. Harrison's Principles of Internal Medicine. 17th ed. The Mc-Graw Hill Companies; 2008. http://www.accessmedicine.com/content.aspx?aID=2900449. Accessed Nov. 24, 2008.
