Micropenis: Encyclopedia II - Micropenis - Causes

Micropenis - Causes

Micropenis can have a variety of causes. Since it is defined statistically, a large proportion of males with micropenis are simply normal but in the lowest percentile of normal size. As for many other conditions, the term "idiopathic" is often used when a cause cannot be determined.

Of the abnormal conditions associated with micropenis, most are conditions of reduced prenatal androgen production or effect. Examples include abnormal testicular development (testicular dysgenesis, Klinefelter syndrome, Leydig cell hypoplasia), specific defects of testosterone or dihydrotestosterone synthesis (17,20-lyase deficiency, 5α-reductase deficiency), androgen insensitivity syndromes, inadequate pituitary stimulation (gonadotropin deficiency) or other forms of congenital hypogonadism. Micropenis can also occur as part of many genetic malformation syndromes not involving the sex chromosomes. It sometimes is a sign of congenital growth hormone deficiency or congenital hypopituitarism. Finally, a gene (HOX9) has been identified which affects penis and digit size without detectable hormone abnormalities.

Pediatric endocrinologists are usually the physicians to whom these boys are referred. After evaluation to detect any of the conditions described above, micropenis can often be treated in infancy with injections of various hormones, such as human chorionic gonadotropin or testosterone.

Most eight to fourteen year old boys referred for micropenis have

1. a penis concealed in suprapubic fat.
2. a large body and frame for which a prepubertal penis simply appears too small.
3. delayed puberty with every reason to expect good future growth.

Adapted from the Wikipedia article "Causes", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki