A micropenis is a penis that is otherwise normally formed but much smaller than average. In infant males, this is indicated by a length of less than 0.75 inches (1.9 centimeters) when stretched. In adult males, the qualifying measurement is 3 inches (7.62 centimeters) when fully erect. There are many conditions that can cause an unusually small penis, but generally, the production or assimilation of testosterone is involved.
Male hypogonadism is a broad medical term describing decreased testosterone production. There are many diagnoses with hypogonadism as a symptom, and a majority of those conditions that begin at infancy or adolescence can result in a micropenis. Hypogonadism is further divided into primary and secondary classes.
In primary hypogonadism, reduced testosterone levels result from a malfunction within the male testicles. When a micropenis presents in infant males, it is sometimes the result of hypogonadism caused by Klinefelter syndrome. Individuals with Klinefelter syndrome have an extra X chromosome, which often results in malformation of the testicles and decreased testosterone production.
Any injury to the testicles before or during early adolescence can cause primary hypogonadism and ultimately result in a micropenis. Injury from physical trauma is obviously dangerous, but damage to the testicles from a mumps infection is also possible. Excess iron levels in the blood can also, in rare cases, lead to underdevelopment.
In secondary hypogonadism, the testicles do not receive the signal to produce testosterone. In these cases, there is usually a malfunction in the pituitary or hypothalamus gland. This can be caused a genetic disorder such as Kallmann syndrome or be the result a number of pituitary disorders. Obesity has also been aligned with secondary hypogonadism.
In infancy, a micropenis is often treated with short-term injections of testosterone. If the penis shows improved growth after three months, it is assumed that increased hormones in puberty will also result in increased length. For adult males, some potential to increase size has been shown using surgical implants. Some herbal remedies have been marketed with guarantees to extend penis length. There are no independent scientific studies to adequately prove these claims.
In the past, parents of a boy born with a micropenis were sometimes advised to have their child undergo gender reassignment surgery. In rare cases, when the child had both a penis and a vagina, this advice was almost universal. As serious emotional effects began to emerge in these children at adolescence, the practice was reexamined. It has since been largely abandoned.