Breast development in men is a condition called gynecomastia. Males with this condition develop breasts similar to those of a woman, made up of firm spongy tissue. The disease is distinct from fatty deposits in the chest of some men that can develop as a symptom of obesity. According to New York University, gynecomastia affects approximately one third of men. Gynecomastia has a number of causes, including genetic factors and behavioral causes.
Hormone Imbalances
Hormones regulate breast development and growth in both males and females. Males typically have higher levels of circulating testosterone, a male hormone, and low levels of estrogen, a female hormone. Since estrogen is one of the hormones involved in breast growth, hormonally balanced males do not develop breasts. According to New York University, the balance of male and female hormones in the body becomes unbalanced in men suffering from gynecomastia. Once diagnosed, the underlying reasons for this hormonal imbalance should be investigated, to rule out the possibility of serious disease.
Marijuana
Marijuana use can cause or contribute to gynecomastia. The active ingredient in marijuana, called delta-9-tetrahydrocannabinol, or THC, has a number of effects on the brain and body. According to the College of Charleston, THC affects the reproductive system and circulating hormone levels. Men who regularly use marijuana may develop gynecomastia over time, since THC promotes the release of a hormone called prolactin from the pituitary gland. The University of California reports that prolactin signals for breast growth and milk production. Sustained high levels of prolactin as a result of regular THC exposure eventually lead to gynecomastia in some men. The University of Texas Health Science Center reports that between 10 and 25 percent of gynecomastia cases are caused by marijuana and other drug use.
Klinefelter's Syndrome
Klinefelter's syndrome is a genetic disorder that affects the sex chromosomes. A normal male has one female X and one male Y chromosome, for a genotype called XY. According to the Klinefelter's Syndrome Association, a male with Klinefelter's has one or more extra copies of the female X chromosome, and may have the genotype XXY, XXXY or XXXXY. Klinefelter's patients have much higher levels of circulating estrogen, and lower levels of testosterone due to insufficient testes development, ultimately resulting in gynecomastia. The University of Texas Health Science Center reports that Klinefelter's syndrome causes 8 percent of total cases of gynecomastia.
