Micropenis
310019
225987584
2008-07-16T09:56:29Z
Hut 8.5
1799532
Reverted edits by [[Special:Contributions/Gregonovich|Gregonovich]] ([[User talk:Gregonovich|talk]]) to last version by Epbr123
{{Infobox_Disease
| Name = Micropenis
| Image = Flacid_micropenis2_highres.jpg
| Caption = A flaccid micropenis
| DiseasesDB = 14839
| ICD10 =
| ICD9 = {{ICD9|752.64}}
| ICDO =
| OMIM =
| MedlinePlus =
| eMedicineSubj = ped
| eMedicineTopic = 1448
| MeshID = }}
'''Micropenis''' is a medical term that describes an unusually small [[penis]]. A common criterion is a dorsal (measured on top) erect [[Human penis size|penile length]] of at least 2.5 [[standard deviation]]s smaller than the [[mean]] [[penis size]].<ref name="pmid7366061">{{cite journal |author=Lee PA, Mazur T, Danish R, ''et al'' |title=Micropenis. I. Criteria, etiologies and classification |journal=The Johns Hopkins medical journal |volume=146 |issue=4 |pages=156–63 |year=1980 |pmid=7366061 |doi=}}</ref> The condition is usually recognized shortly after [[Childbirth|birth]]. The term is most often used medically when the rest of the penis, [[scrotum]], and [[perineum]] is without [[ambiguous genitalia|ambiguity]] such as [[hypospadias]].
==Causes==
[[Image:Erect small5.jpg|thumb|right|An [[erection|erect]] penis with the micropenis condition.]]
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]], [[5-alpha-reductase deficiency|5α-reductase deficiency]]), [[androgen insensitivity syndrome]]s, 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, several [[Homeobox]] genes have been identified which affects penis and digit size without detectable hormone abnormalities.
After evaluation to detect any of the conditions described above, micropenis can often be treated in infancy with injections of various [[hormone]]s, such as [[human chorionic gonadotropin]] or [[testosterone]].
Most eight to fourteen year old boys referred for micropenis do not have the micropenis condition. Such concerns are usually explained by one of the following:
# a penis concealed in [[suprapubic fat]] (extra fat around the mons pubis).
# a large body and frame for which a prepubertal penis simply appears too small.
# [[delayed puberty]] with every reason to expect good future growth.
==Treatment==
===Hormone treatment===
[[Image:Men with micropenis.jpg|thumb|Man with micropenis, hypogonadism and gynecomastia]]
Growth of the penis both before birth and during childhood and puberty is strongly influenced by [[testosterone]] and, to a lesser degree, [[growth hormone]], but their value in the treatment of micropenis is mainly limited to conditions of hormone deficiency such as [[hypopituitarism]] or [[hypogonadism]].
Regardless of the cause of micropenis, if it is recognized in infancy, a brief course of testosterone is often prescribed<ref name="pmid15201804">{{cite journal |author=Ishii T, Sasaki G, Hasegawa T, Sato S, Matsuo N, Ogata T |title=Testosterone enanthate therapy is effective and independent of SRD5A2 and AR gene polymorphisms in boys with micropenis |journal=J. Urol. |volume=172 |issue=1 |pages=319–24 |year=2004 |pmid=15201804 |doi=10.1097/01.ju.0000129005.84831.1e}}</ref> (usually no more than 3 months). This will usually induce a small amount of growth, confirming the likelihood of further growth at puberty, but rarely achieves normal size. No additional testosterone is given during childhood to avoid unwanted [[virilization]] and [[bone maturation]]. (There is also some evidence that premature administration of testosterone can lead to reduced penis size in the adult.)<ref name="pmid7609189">{{cite journal |author=McMahon DR, Kramer SA, Husmann DA |title=Micropenis: does early treatment with testosterone do more harm than good? |journal=J. Urol. |volume=154 |issue=2 Pt 2 |pages=825–9 |year=1995 |pmid=7609189|doi=10.1016/S0022-5347(01)67175-1}}</ref>
Testosterone treatment is resumed in adolescence only for boys with hypogonadism. Penile growth is completed at the end of puberty, similarly to the completion of [[human height|height growth]], and provision of extra testosterone to post-pubertal adults will produce little or no further growth.
===Surgery===
Because hormone treatment rarely achieves average size, a number of surgical techniques like [[phalloplasty]] for [[penis enlargement]] have been devised and performed but are not generally considered successful enough to be widely adopted and are rarely performed in childhood.
In extreme cases of micropenis, there is barely any shaft, and the glans appears to sit almost on the pubic skin. From the 1960s until the late 1970s, it was not unusual for [[sex reassignment]] and [[history of intersex surgery|surgery]] to be recommended. This was especially likely if evidence suggested that response to additional testosterone and pubertal testosterone would be poor. If parents accepted, the boy would be reassigned and renamed as a girl, and surgery performed to remove the testes and construct an artificial [[vagina]]. This was based on three now questioned assumptions:
#gender identity and sex differences were solely a matter of social learning rather than biology.
#a male with a penis too small to put into a vagina could not find a satisfactory social and sexual place in society.
#a functionally acceptable vagina could be constructed surgically.
The center most known for this approach ([[Johns Hopkins Hospital]]) performed twelve such reassignments between 1960 and 1980, most notably, that of [[David Reimer]], overseen by Dr. [[John Money]]. By the mid-1990s reassignment was less often offered, and all three premises had been challenged. Former subjects of such surgery, vocally dissatisfied with adult outcome, played a large part in discouraging this practice. As a result, sexual reassignment is rarely performed today for severe micropenis (although the issue of raising the child as a girl is sometimes still discussed.)<ref name="pmid10228285">{{cite journal |author=Calikoglu AS |title=Should boys with micropenis be reared as girls? |journal=J. Pediatr. |volume=134 |issue=5 |pages=537–8 |year=1999 |pmid=10228285 |doi=}}</ref> Much inaccurate or exaggerated folklore on this topic is available on the internet. (See [[History of intersex surgery]] for a more complete discussion of this issue.)
==See also==
* [[Hypogonadism]]
* [[Intersexuality|Intersex]]
* [[Human penis size|Penis size]]
==References==
<references/>
==External links==
*[http://www.jhu.edu/~jhumag/0900web/babes.html Into the Hands of Babes], by Melissa Hendricks, ''[[Johns Hopkins Magazine]]''
*[http://bms.brown.edu/faculty/f/afs/Gender%20Self%20reassignment.pdf Gender Self Reassignment in an XY Adolescent Female with Ambiguous Genitalia], from ''[[Pediatrics (journal)|Pediatrics]]'' ([[PDF]])
*[http://www.nature.com/ijir/journal/v17/n3/abs/3901292a.html Effect of penile size on nocturnal erections: evaluation with NPTR testing with men having micropenis] from the ''[[International Journal of Impotence Research]]''
{{Congenital malformations of genital organs and urinary system}}
[[Category:Andrology]]
[[Category:Penis]]
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[[it:Micropenia]]
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[[pt:Micropênis]]
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