Breasts are normally a female characteristic, developing at puberty in the early teenage years, but any human, of any age or either sex, is able to develop breasts if given the sex hormone oestrogen. Those men who have decided to change their apparent sex, and those who wish to be transvestites, may take oestrogen in order to develop breasts, but there are a number of medical conditions that can also cause gynaecomastia (abnormal breast enlargement).
Some boys going through puberty find that they are developing small lumps of tissue behind their nipples. This is caused by an imbalance in the sex hormones during this delicate stage of development. Most settle in a few months or a year, but a small number continue to develop excessive amounts of breast tissue and require an operation to remove it.
In men the menopause (andropause) occurs in the seventies, while in women it occurs in the late forties and early fifties. As testosterone levels drop in elderly men, the small amount of oestrogen that is present in the system of all men, may no longer be suppressed by the testosterone, and start stimulating breast tissue development.
Women taking oestrogen as a hormone replacement therapy after the menopause, or in the oral contraceptive pill, may notice an increase in their breast size.
Obesity is an often overlooked cause for breast enlargement in both sexes, as fat may deposit in the breast area more easily than in the surrounding chest tissue.
Other causes of breast enlargement include:
- liver failure (oestrogen normally produced by a man or woman may not be broken down and removed from the body at the normal rate),
- cancer or tumours of the testicle may prevent the normal production of testosterone,
- in some cases (e.g. teratoma) may start to produce oestrogen instead,
- Klinefelter syndrome (only affects males who have additional X chromosomes matched with a single Y chromosome),
- Addison’s disease (adrenal glands do not produce sufficient quantities of vital hormones),
- a rare form of lung cancer (oat cell carcinoma) will affect sex hormone balance and cause breast enlargement in both sexes.