Causes of Gynecomastia
Diagnosis of Gynecomastia
History of gynecomastia treatment
Treatment of gynecomastia


endocrine system click here to learn about the pineal Hormonal imbalance is at the heart of gynecomastia. Therefore, it is of value to learn something about the body's hormone, ("endocrine") system.

The endocrine system is a system of glands that secrete different "hormones" to regulate the body. Hormones regulate many functions, including, growth, tissue function, and the body's use of energy.

The glands of this system are ductless and very vascular, liberating their chemicals directly into the blood stream. ("Exocrine glands," such as salivary glands, sweat glands, and the breast, are less vascular and have ducts or tubes that carry their secretions to where it is needed.)

(Most of the important endocrine glands are depicted in the artwork to the left. Click on each name to learn more about the gland's function.)

"Male" hormones, ("androgens"), and female hormones, ("estrogens") are made by normal individuals of both sexes. It is the presence of a much higher amount of androgens that makes one appear male, and the primacy of estrogen that makes another female. Since breast growth and development are very much under the influence of estrogen, breast development may eventuate when processes within the male disturb the usual balance between androgens and estrogens. (-See Video Intro-)

Physiological Gynecomastia

Physiologic gynecomastia occurs in newborns and in adolescents at puberty. Newborns may show breast development from the action of persistent maternal and placental estrogens. The breast tissue ordinarily disappears in a few weeks as hormone levels decrease. Neonatal gynecomastia requires no treatment, but before involution occurs, it is possible for the tiny breasts to produce some milk, (5% of full-term newborns produce such "witch's milk").

During puberty, as sex hormones begin to flood the young person's body, there can occasionally be a short-lived imbalance between testosterone and estradiol in the male, with the estrogen levels being high enough to stimulate breast growth. (Some also believe that certain individuals may have a heightened hormone receptor sensitivity to normal levels of estrogen.) Many suggest that nearly two thirds of all adolescent males experience some breast development of this type. The average age of onset is 13 years, and the breasts are often asymmetrically developed and tender. For most, the offending stimulus is gone within months and the gynecomastia slowly disappears. Experience shows us that those cases that have not resolved spontaneously in two years or less are unlikely to do so, however. Individuals with what might be called, "persistent adolescent gynecomastia" make up a large percentage of the adult group ultimately presenting for treatment.

Pathological Gynecomastia

Pathological forms of gynecomastia are due to diseases that create testosterone deficiency, estrogen excess, or the increased peripheral conversion of androgens into active estrogens.

Disorders that can lead to decreased testosterone production include:

Disorders that can lead to increased estrogen production or decreased clearance include:

aromatization of testosteroneExcess estrogen can be the result of excess extrogen production, or may eventuate when there is too much peripheral conversion of androgens. In a process called "aromatization," the body's tissues employ enzymatic alteration in testosterone to generate estrogen. The enzyme "aromatase" transforms the the A-ring of steroids to a chemical "aromatic state" through oxidation and elimination of a methyl group. This appears to be important in the pathogenesis of the gynecomastia that is associated with aging, obesity, puberty, liver and thyroid disease and certain neoplasms.

Medication-related Gynecomastia

Many believe that up to 20% of those presenting with post-adolescent gynecomastia developed their problems as the result of medication-related effects. The offending medications can be divided into those prescribed for real medical use, and those used privately and/or illicitly.

Prescribed medications:

gynecomastia from anti-androgen use
  • Antiandrogens and gonadotropin releasing hormone analogs used in prostate cancer
  • Anti-retrovirals for treatment of HIV
  • Dutasteride(Avodart)
  • Chlorpromazine
  • Cimetidine
  • Diazepam (valium)
  • Digoxin (digitalis)
  • Estrogen
  • Human chorionic gonadotropin (HCG)
  • Isoniazid (INH)
  • Ketoconazole
  • Methadone
  • Methydopa
  • Metoclopramide
  • Metronidazole
  • Nifedipine
  • Omeprazole
  • Penicillamine
  • Phenothiazine
  • Spironolactone
  • Glucocorticosteroids
  • Tamoxifen
  • Tricyclic antidepressants
  • Verapamil

The other drugs that are commonly associated with gynecomastia are self-prescribed:

  • Alcohol
  • Anabolic steroids
  • Heroin
  • Marijuana

Finally, an interesting correlation has been shown to exist between the use of topical balms and soaps containing lavendar or tea-tree oils and gynecomastia. In vitro studies confirmed that lavender oil and tea tree oil possess weak estrogenic and antiandrogenic activities, and may contribute to an imbalance in estrogen and androgen pathway signaling. Since these oils are present in a number of products, including shampoos, soaps, and body lotions, it is interesting to wonder if they might elicit similar endocrine-disrupting effects in prepubertal girls, adolescents and women.

The Common Scenarios

While all the above pathologies (as well as others not listed) can be associated with gynecomastia, the overwhelming majority of cases presenting to the average medical practitioner will be those caused by persistent adolescent breast growth, obesity, old age and medication use. The majority of these can be diagnosed with history and physical examination alone. However, as detailed in the "Diagnosis" section, a more rigorous diagnostic work-up can at times be warranted.

Although not a common disease, male breast cancer deserves particular attention because of its sinister potential when diagnosis is delayed. Please review the details in the section of this site regarding diagnosis.