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Gynecomastia is the development of abnormally large breasts in males. It is related to the excess growth of breast tissue, rather than excess fat tissue.


Breast growth is directed exclusively by female hormones—estrogens. Although men have some estrogen in their system, it is usually insufficient to cause much breast enlargement because it is counterbalanced by male hormones—androgens. Upsetting the balance, either by more of one or less of the other, results in the male developing female characteristics, breast growth being foremost.

At birth both male and female infants will have little breast buds from their mother's hormones. These recede until adolescence, when girls always, and boys sometimes, have breast growth. At this time, the boy's breast growth is minimal, often one-sided and temporary.

Extra or altered sex chromosomes can produce inter-sex problems of several kinds. Breast growth along with male genital development is seen in Klinefelter syndrome—the condition of having an extra X (female) chromosome—and a few other chromosomal anomalies. One of the several glands that produce hormones can malfunction for reasons other than chromosomes. Failure of androgen production is as likely to produce gynecomastia as overabundant estrogen production. Testicular failure and castration can also be a cause. Some cancers and some benign tumors can make estrogens. Lung cancer is known to increase estrogens.

If the hormone manufacturing organs are functioning properly, problems can still arise elsewhere. The liver is the principle chemical factory in the body. Other organs like the thyroid and kidneys also effect chemical processes. If any of these organs are diseased, a chemical imbalance can result that alters the manufacturing process. Men with cirrhosis of the liver will often develop gynecomastia from increased production of estrogens.

Finally, drugs can also cause breast enlargement. Estrogens are given to men to treat prostate cancer and a few other diseases. Marijuana and heroin, along with some prescription drugs, have estrogen effects in some men. On the list are methyldopa (for blood pressure), cimetidine (for peptic ulcers), diazepam (Valium), anti-depressants, and spironolactone (a diuretic).


Related Articles

Breast Enlargement in Men
Breast enlargement in men is called gynecomastia . Gynecomastia can occur during early childhood or puberty. Older men can also suffer from gynecomastia due to hormonal changes or medication side effects. Breast swelling can also result from abn  More »


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