Micropenis is a medical term that describes an unusually small penis. A common criterion is a dorsal (measured on top) erect penile length at least 2.5 standard deviations smaller than the mean penis size.^[1] The condition is usually recognized shortly after birth. The term is most often used medically when the rest of the penis, scrotum, and perineum is without ambiguity such as hypospadias. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The Disease Bold textDatabase is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... The penis (plural penises, penes) is an external male sexual organ. ... Human penis size refers to the length and width of human male genitalia. ... In probability and statistics, the standard deviation of a probability distribution, random variable, or population or multiset of values is a measure of the spread of its values. ... This article is about mathematical mean. ... Penis size is of great concern to many men. ... Parturition redirects here. ... In some male mammals, the scrotum is a protuberance of skin and muscle containing the testicles. ... In human anatomy, the perineum, also called the taint, or gooch, is generally defined as the surface region in both males and females between the pubic symphysis and the coccyx. ... An intersexual is a person (or individual of any unisexual species) who is born with genitalia and/or secondary sexual characteristics of indeterminate sex, or which combine features of both sexes. ... Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urethral meatus (opening). ...

Causes

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, several Homeobox genes have been identified which affects penis and digit size without detectable hormone abnormalities. Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates by binding to androgen receptors. ... XXY karyotype Klinefelters syndrome is a condition caused by a chromosome abnormality in males (specifically, a nondisjunction); sufferers have a pair of X sex chromosomes instead of just one. ... Testosterone is a steroid hormone from the androgen group. ... (Redirected from 17,20-lyase deficiency) Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia resulting from a defect in the gene for the enzyme P450c17, which mediates several key transformations in the synthesis of both cortisol and sex steroids. ... It has been suggested that this article or section be merged with Guevedoche. ... Androgen insensitivity syndrome (AIS, or Androgen resistance syndrome) is a set of disorders of sexual differentiation that results from mutations of the gene encoding the androgen receptor. ... Located at the base of the skull, the pituitary gland is protected by a bony structure called the sella turcica. ... Gonadotropins are protein hormones secreted by gonadotrope cells of the pituitary gland of vertebrates. ... Hypogonadism is a medical term for a defect of the reproductive system which results in lack of function of the gonads (ovaries or testes). ... Growth hormone deficiency is the medical condition of inadequate production of growth hormone (GH) and its effects on children and adults. ... Hypopituitarism is a medical term describing deficiency (hypo) of one or more hormones of the pituitary gland. ... A homeobox is a DNA sequence found within genes that are involved in the regulation of development (morphogenesis) of animals, fungi and plants. ...

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. For other uses, see Hormone (disambiguation). ... Human chorionic gonadotropin (hCG) is a peptide hormone produced in pregnancy, that is made by the embryo soon after conception and later by the syncytiotrophoblast (part of the placenta). ... Testosterone is a steroid hormone from the androgen group. ...

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:

1. a penis concealed in suprapubic fat (extra fat around the mons pubis).
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.

Puberty is described as delayed when a boy or girl has passed the usual age of onset of puberty with no physical or hormonal signs that it is beginning. ...

Treatment

Hormone treatment

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. Testosterone is a steroid hormone from the androgen group. ... Growth hormone (GH) or somatotropin (STH) is a protein hormone which stimulates growth and cell reproduction in humans and other animals. ... Hypopituitarism is a medical term describing deficiency (hypo) of one or more hormones of the pituitary gland. ... Hypogonadism is a medical term for a defect of the reproductive system which results in lack of function of the gonads (ovaries or testes). ...

Regardless of the cause of a micropenis, if it is recognized in infancy, a brief course of testosterone is often prescribed^[2] (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.)^[3] In biology and medicine, virilization refers to the development of changes which make a male body different from a female body. ... Bone age is a way of describing the degree of maturation of a childs bones. ...

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 height growth, and provision of extra testosterone to post-pubertal adults will produce little or no further growth. Stature redirects here. ...

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. Phalloplasty refers to the (re-)construction of a penis or, sometimes, to artificial modification of the penis by surgery, often for cosmetic purposes. ... Penis enlargement procedures (sometimes referred to as male enhancement procedures in spam email and television advertisements) are techniques alleged to make the human penis larger. ...

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 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: Sex assignment refers to the assigning of sex at the birth of a baby. ... Intersex surgery is one of several terms referring to surgery performed to correct birth defects due to intersex conditions or other causes, as well as early injuries of the genitalia. ... The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ...

1. gender identity and sex differences were solely a matter of social learning rather than biology.
2. a male with a penis too small to put into a vagina could not find a satisfactory social and sexual place in society.
3. 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.)^[4] 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.) The Dome of the Johns Hopkins Hospital as seen from Broadway. ... David Reimer (August 22, 1965 – May 4, 2004) was a Canadian man who was born as a healthy boy, but was sexually reassigned and raised as female after his penis was inadvertently destroyed during circumcision. ... John William Money, Ph. ... Intersex surgery is one of several terms referring to surgery performed to correct birth defects due to intersex conditions or other causes, as well as early injuries of the genitalia. ...

Micropenis in studies

A relatively high incidence of alleles believed to cause the micropenis condition have been found in a Japanese study of patients with micropenis, consisting of 81 Japanese patients. The presence of a micropenis in these subjects is considered to be due to a higher mutation rate for the SRD5A2 gene, which encodes for the enzyme 5{alpha}-reductase-2 and plays a role in male sex differentiation.^[5] The mutation led to decreased expression of the enzyme, which in turn results in penises with erect lengths of -2.5 standard deviations. In the case of the Japanese sample, hormone treatments were also studied and found to be effective, resulting in penis lengths at nearly the average of age-matched Japanese controls (2-3 cm). After extended study of various micropenises, it can be concluded that this condition has severe effects both mentally and physically for the patient. 5-alpha reductase is an enzyme that converts testosterone, the male sex hormone, into the more potent dihydrotestosterone: Note the major difference -- the Δ4,5 double-bond on the A (leftmost) ring. ...

See also

• Hypogonadism
• Intersex
• Penis size

Hypogonadism is a medical term for a defect of the reproductive system which results in lack of function of the gonads (ovaries or testes). ... Intersexuality is the state of a person whose sex chromosomes, genitalia and/or secondary sex characteristics are determined to be neither exclusively male nor female. ... Human penis size refers to the length and width of human male genitalia. ...

References

1. ^ Lee PA, Mazur T, Danish R, et al (1980). "Micropenis. I. Criteria, etiologies and classification". The Johns Hopkins medical journal 146 (4): 156-63. PMID 7366061. 
2. ^ Ishii T, Sasaki G, Hasegawa T, Sato S, Matsuo N, Ogata T (2004). "Testosterone enanthate therapy is effective and independent of SRD5A2 and AR gene polymorphisms in boys with micropenis". J. Urol. 172 (1): 319-24. doi:10.1097/01.ju.0000129005.84831.1e. PMID 15201804. 
3. ^ McMahon DR, Kramer SA, Husmann DA (1995). "Micropenis: does early treatment with testosterone do more harm than good?". J. Urol. 154 (2 Pt 2): 825-9. PMID 7609189. 
4. ^ Calikoglu AS (1999). "Should boys with micropenis be reared as girls?". J. Pediatr. 134 (5): 537-8. PMID 10228285. 
5. ^ Micropenis and the 5{alpha}-Reductase-2 (SRD5A2) Gene: Mutation and V89L Polymorphism Analysis in 81 Japanese Patients -- Sasaki et al. 88 (7): 3431 -- Journal of Clinical Endocrinology & Metabolism. Retrieved on 2007-09-15.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 258th day of the year (259th in leap years) in the Gregorian calendar. ...

External links

• Into the Hands of Babes, by Melissa Hendricks, Johns Hopkins Magazine
• Gender Self Reassignment in an XY Adolescent Female with Ambiguous Genitalia, from Pediatrics (PDF)
• Effect of penile size on nocturnal erections: evaluation with NPTR testing with men having micropenis from the International Journal of Impotence Research