Although clitoromegaly denotes just a clitoris larger than expected (thus involving some uncertainty about what can be defined as normal), it is commonly seen as a congenital anomaly of the genitalia.
In Atlas of Human Sex Anatomy (1949) by Dr. Robert Latou Dickinson, the normal clitoris is defined as having a crosswise width of 3 to 4 mm. (0.12 - 0.16 inches) and a lengthwise width of 4 to 5 mm (0.16 - 0.20 inches). On the other hand, in Obstetrics and Gynecology medical literature, a frequent definition of clitoromegaly is when there is a CI of greater than 35 mm2 (0.05 inches2), which is almost twice the size given above for an average sized clitoral hood .
In acquired clitoromegaly the main cause is due to endocrine hormonal imbalance affecting the adult women, including polycystic ovarian syndrome (PCOS). Acquired clitoromegaly may also be caused by pathologies affecting the ovaries and other endocrine glands. These pathologies may include virulent (such as arrhenoblastoma) and neurofibromatosic tumors. This can also be caused by clitoral cysts. In addition, sometimes there may be no obvious or hormonal reason.
Clitoromegaly may be acquired through use of anabolic steroids or testosterone supplements, both of which can cause enlargement of the clitoris. This occurs in Female to Male Transsexuals (FtM) after a period of hormone replacement therapy. Like FtM transsexuals, female bodybuilders who use androgens may also experience enlargement of the clitoris and increases in libido. Women who use testosterone for therapeutic reasons (treating low libido, averting osteoporosis, as part of an anti-depressant regimen, etc) may also experience some enlargement of the clitoris although the dosages warranted for these conditions is much lower.