AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Microphallus, or micropenis, is defined as a stretched penile length of less than 2.5 standard deviations (SDs) below the mean for age. Traditionally, the term micropenis refers to a penis that is otherwise normally formed, and the term microphallus has been used when associated hypospadia is present.

The mean stretched penile length in a full-term newborn male is 3.5 cm. Measurements of less than 2.5 cm (2.5 SDs below the mean) in a full-term newborn male meet the definition of micropenis and warrant evaluation. Penile growth is essentially linear during mid-to-late gestation. Tuladhar et al (1998) reported the following formula to describe the relationship between penile length and gestational age for infants born at 24-36 weeks gestation:¹

Penile length in centimeters = 2.27 + 0.16 X (gestational age in weeks)

Although micropenis can be considered a form of ambiguous genitalia, the presence of a normal scrotum and palpable testes indicates a high probability of a normal male karyotype. If the testes are not palpable, the penile urethra is absent, or both, the examination is better described as ambiguous, and an evaluation and counseling for disorders of sexual development should be performed.

After the first few years of life, the penis grows very little until puberty when testosterone levels begin to rise. Mean stretched penile lengths and 2.5 SDs below the mean for various age groups can be found in the popular Harriet Lane Handbook (table 9-26, 17th ed).²

Occasionally, older boys are brought to physicians for evaluation because of concerns of small genitalia. These boys are usually prepubertal and obese. Most often, these individuals have normal penis size based on stretched penile length, and the apparent smallness is secondary to the penis being concealed in the suprapubic fat pad. However, if the penis does measure less than 2.5 SDs below the mean (approximately 4 cm), further evaluation is indicated.

Pathophysiology

Fetal production of testosterone and its peripheral conversion to dihydrotestosterone (DHT) is necessary for normal male development. Early in gestation, placental human chorionic gonadotropin (hCG) stimulates the developing testes to produce testosterone through binding to the luteinizing hormone (LH) receptor. By approximately 14 weeks' gestation, the fetal hypothalamic-pituitary-gonadal axis is active, and testosterone production falls under the influence of fetal LH. Therefore, penile growth after the first trimester depends on fetal testosterone production. Testosterone is  peripherally converted by the enzyme 5-alpha reductase to the more potent androgen DHT, which is responsible for virilization of the male external genitalia. Finally, intact peripheral androgen receptors are necessary for normal male development.

Shortly after birth, gonadotropin (LH and follicle stimulating hormone [FSH]) and testosterone production decrease. Beginning at about age 1 week, gonadotropin and testosterone levels begin to rise again to pubertal levels, peaking at age 1-3 months, and then decreasing to prepubertal levels by age 6 months. After age 6 months, the little subsequent penile growth that occurs parallels general somatic growth. With the onset of puberty penis growth resumes because of increases in testosterone production. Growth hormone also plays a role in penis growth because micropenis has been observed in children with isolated growth hormone deficiency.

Micropenis may be caused by a defect anywhere along the hypothalamic-pituitary-gonadal axis, a defect in peripheral androgen action, isolated growth hormone deficiency, or a primary structural anomaly or it may be part of a genetic syndrome. The most common cause of micropenis is abnormal hypothalamic or pituitary function. In the absence of normal hypothalamic or pituitary function, a normally shaped penis may develop due to maternal hCG effect on fetal testosterone production, but adequate penile growth does not occur after 14 weeks' gestation when testosterone production depends on intact fetal pituitary LH secretion.  Failure of adequate testosterone production toward the end of gestation due to a primary testicular disorder can also result in inadequate penis growth. 

Micropenis can also occur in children with LH-receptor defects and defects in testosterone biosynthesis (eg, 17-beta hydrosysteroid dehydrogenase deficiency). The genitalia of individuals with LH-receptor defects vary from a normal female appearance to a male with micropenis. Individuals with 17-beta hydroxysteroid dehydrogenase deficiency most often have female-appearing genitalia and, less often, ambiguous genitalia. 

Defects in peripheral androgen action include 5-alpha reductase deficiency (failure of conversion of testosterone to DHT) and partial androgen insensitivity syndrome (PAIS) due to an androgen receptor defect. However, most children with these conditions have varying degrees of incomplete labioscrotal fusion, resulting in hypospadias and genital ambiguity.

Lastly, genetic syndromes in which micropenis may be a feature include Prader-Willi, Klinefelter, and Noonan syndromes, among others (see Causes).

Mortality/Morbidity

When micropenis is associated with hypopituitarism and hypoadrenalism, the infant can develop hypoglycemia, electrolyte abnormalities, hypotension, and shock. Infants with midline defects and those with optic nerve hypoplasia or aplasia deserve particular attention because these defects may point to pituitary hormone deficiencies. Failure to recognize this association in an ill neonate can result in death. Infants who survive the newborn period may exhibit varying degrees of poor growth and failure to thrive, depending on potential associated hormone deficiencies or genetic syndrome.

Psychosocial concerns can arise over issues such as gender identity, normal standing urination, physical appearance, and sexual performance. These concerns should be addressed with early evaluation, treatment and counseling, if appropriate.

In cases of extreme micropenis, especially if associated with other genital anomalies (eg, cryptorchidism, hypospadias), gender reassignment is sometimes considered. However, the family needs to be intimately involved in this decision, and counseling from a center with a multidisciplinary team skilled at gender reassignment should be pursued.

Sex

By definition, microphallus is an exclusively male condition. However, distinguishing between a male with micropenis and cryptorchidism and a female with clitoromegaly is important and may be difficult.

Age

Micropenis is most often recognized and evaluated in the immediate newborn period, but delays in evaluation may also occur.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Neonatal hypoglycemia, often in the first 24 hours of life, is associated with other pituitary hormone deficiencies, including panhypopituitarism, growth hormone deficiency, and adrenal insufficiency. Other features that may be associated with hypopituitarism during the neonatal period include breech delivery, optic nerve hypoplasia or aplasia, nystagmus, other midline defects, and cholestasis with prolonged direct hyperbilirubinemia.
• Poor growth or failure to thrive is also associated with other pituitary hormone deficiencies.
• An abnormal sense of smell (anosmia or hyposmia) suggests Kallmann syndrome (hypogonadotropic hypogonadism with abnormal olfaction).
• Other congenital anomalies may provide clues to a genetic syndrome.
• Family history of similarly affected children could suggest a familial form of hormonal deficiency (autosomal recessive), defect in steroidogenesis (autosomal recessive), or androgen insensitivity (X-linked). Family history of unexplained death in the first year of life could also suggest pituitary hormone deficiencies, adrenal insufficiency, or both.

Physical

• The infant or child with micropenis should be thoroughly examined for dysmorphic features and other congenital defects. This examination should include careful inspection of the face and mouth for cleft lip or palate or other indications of midfacial hypoplasia.
• Abnormal growth velocity suggests growth hormone deficiency with or without other pituitary hormone deficiencies.
• A thorough examination of the genitalia, including proper measurements of the stretched penis length and location and size of the testes, is important.
• • The proper technique for measuring the penis is to use a rigid ruler held firmly against the symphysis pubis at a right angle. Firm but gentle traction is placed on the penis to stretch it upward along the ruler to the point of increased resistance
  • An alternate, less traumatic method is to use the index finger of one hand as a gauge pressed against the symphysis. Gentle traction is placed on the penis, the index finger of the other hand is used to mark the length on the gauge finger, and a tape measure is used to determine the length.
  • One or both testes may be abnormally descended because testosterone also plays a role in testicular descent.

Causes

Most cases of micropenis are due to fetal testosterone deficiency. Testosterone deficiency may be caused by a defect anywhere along the hypothalamic-pituitary-gonadal axis or a defect in peripheral androgen action (5-alpha reductase deficiency or PAIS). Micropenis may also be caused by isolated growth hormone deficiency. Additionally, it can occur as a primary idiopathic structural anomaly or may be associated with a genetic syndrome. The most common cause of micropenis is abnormal hypothalamic or pituitary function that leads to hypogonadotropic hypogonadism. The next most common cause is a primary testicular disorder that leads to hypergonadotropic hypogonadism.

• Conditions associated with hypogonadotropic hypogonadism
• • Multiple pituitary hormone deficiency: This condition may be secondary to transcription factor mutations (eg, PROP-1, LHX3); however, in most instances, genetic evaluation is not part of the routine diagnostic evaluation.
  • Kallmann syndrome: Anosmia (lack of sense of smell) or hyposmia is a prominent feature of Kallmann syndrome, which occurs in 1 per 10,000 males. The underlying abnormality is failure of migration of gonadotropin-releasing hormone (GnRH) and olfactory neurons from the olfactory placode to their proper locations in the hypothalamus and olfactory bulb, respectively. About half of males with Kallmann syndrome are born with a micropenis. The inheritance pattern is autosomal dominant (FGFR1/KAL-2 gene), autosomal recessive, or X-linked recessive (KAL-1 gene). Associated anomalies may include cleft lip and palate, congenital heart disease, renal agenesis, sensorineural deafness, visual abnormalities, synkinesia (mirror image movements), cerebellar ataxia, short metacarpals, or pes cavus. Abnormal or absent olfactory bulbs or sulci (folds) are seen on brain MRI in 90% of patients.
  • Septo-optic dysplasia (SOD): Major features of SOD include the triad of absent septum pellucidum, optic nerve hypoplasia, and hypopituitarism. Wandering nystagmus may be noted. The multiple pituitary hormone deficiencies may be present at birth or develop over years. Mutations in the HESX1 gene (RPX) have been associated with SOD.
  • Idiopathic hypogonadotropic hypogonadism: The sense of smell is normal in this condition, differentiating it from Kallman syndrome.
• Conditions associated with decreased testosterone production and hypergonadotropic hypogonadism
• • Anorchia: In this condition of absent testes in an individual with a normal male karyotype, micropenis results when testicular degeneration occurs after approximately 12-14 weeks' gestation. The testicular degeneration is due to torsion or other vaso-occlusive event in utero.
  • LH-receptor defects: Autosomal recessive mutations are found in the LHCGR gene in this rare condition and cause Leydig cell hypoplasia in males. The genital phenotype varies from normal-appearing female to male with micropenis.
  • Defects in testosterone steroidogenesis: Incomplete forms of 17 beta-hydroxysteroid dehydrogenase deficiency type 3 can cause micropenis, but the genitalia are most often female in appearance or less often ambiguous. The enzyme 17-beta-hydroxysteroid dehydrogenase normally converts androstenedione to testosterone. In the deficiency state, the androstenedione-to-testosterone ratio is elevated (after hCG stimulation in the prepubertal state) and is expressed as a testosterone-to-androstenedione ratio of less than 0.8. These individuals undergo profound virilization at puberty.
• Deficiency of 5-alpha reductase: 5-alpha reductase peripherally converts testosterone to the more potent DHT, which is necessary for virilization of the male external genitalia. The genitalia in most children with this autosomal recessive condition are usually more ambiguous, with varying degrees of incomplete labioscrotal fusion and hypospadias. The hallmark biochemical abnormality is an elevated testosterone-to-DHT ratio (usually >30:1) after hCG stimulation if prepubertal. These individuals also undergo profound virilization at puberty.
• PAIS: PAIS is due to a defect in the androgen receptor. Isolated micropenis is not typically a manifestation of PAIS because the genitalia are usually more ambiguous. Gonadotropin and testosterone levels are elevated in this condition. Because the gene that codes for the androgen receptor is located on the X chromosome, PAIS is inherited in an X-linked manner.
• Growth hormone deficiency
• Genetic syndromes
• • Klinefelter syndrome (47,XXY) and other poly X syndromes: Features of this syndrome include hypergonadotropic hypogonadism, tall stature, gynecomastia, small firm testes, increased leg length, and increased risk for learning difficulties.
  • Prader-Willi syndrome: Features of this syndrome include hypogonadotropic hypogonadism, cryptorchidism, hypotonia in infancy, failure to thrive in infancy with later hypothalamic obesity, developmental delay, short stature, small hands and feet, emotional instability (perseveration, obesessions and compulsions), almond-shaped eyes, and triangular mouth. This syndrome occurs in 1:20,000 live births.
  • Bardet-Biedl syndrome: Features of this syndrome include hypogonadotropic hypogonadism, developmental delay, retinitis pigmentosa, obesity, short stature, polydactyly, renal dysplasia leading to end-stage renal disease, hepatic fibrosis, and hearing loss. Inheritance of this syndrome is in an autosomal recessive pattern.
  • Noonan syndrome: Features of this syndrome include short stature, webbed neck, hypertelorism, ptosis, low posterior hairline, low-set ears, pectus excavatum, cryptorchidism, valvular pulmonary stenosis, lymphedema, and bleeding abnormalities. Noonan syndrome is inherited in an autosomal dominant manner, although approximately half of all cases represent new mutations. 
  • CHARGE syndrome: The syndrome is defined by coloboma, heart disease, atresia choanae, retarded growth and development, genital anomalies and hypogonadism, and ear anomalies and deafness. Neuropathic bladder, hydronephrosis, vesicoureteral reflux, and ureteropelvic junction obstruction may also be observed. Given the renal and urinary tract abnormalities that can occur, bladder and renal ultrasonography and voiding cystourethrography (VCUG) are indicated in those suspected of having this syndrome.
  • Robinow syndrome: Features of the syndrome include hypergonadotropic hypogonadism, cryptorchidism, hypoplastic or absent genitalia, flat facial profile with prominent nares, hypertelorism, low-set ears, short forearms, rib abnormalities, and spinal abnormalities. The inheritance pattern of this syndrome is autosomal dominant.  
  • Rud syndrome: Features of this syndrome include hyposmia, developmental delay, congenital ichthyosis, epilepsy, and short stature.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

X-linked adrenal hypoplasia congenita: Hypogonadotropic hypogonadism is associated with X-linked adrenal hypoplasia congenita and usually presents with lack of pubertal development. Primary adrenal failure occurs in infancy or early childhood. Mutations in the DAX1 gene are implicated.

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Chromosomal analysis is recommended to confirm chromosomal sex and to evaluate for associated genetic syndromes. If Prader-Willi syndrome is suspected, chromosomal analysis looking for a 15q11-13 band deletion of the paternally derived chromosome (70%), maternal uniparental disomy (25%), or methylation-specific paternal defect (5%) should be undertaken.
• Gonadotropins (LH and FSH) reach pubertal levels in healthy male infants, peaking at age 1-3 months. Excessively high or low values during this time help to narrow the differential diagnoses.
• Testosterone and DHT levels, before and after hCG stimulation, can be measured to evaluate the responsiveness of the testes to gonadotropin stimulation and for 5-alpha reductase deficiency (indicated by an increased testosterone-to-DHT ratio).
• Observe infants with micropenis (especially if other abnormalities associated with hypopituitarism are present) for evidence of metabolic derangements.
• • If hypoglycemia occurs, obtain a critical sample immediately before intravenous glucose is administered. 
  • The critical sample should include glucose, insulin, growth hormone, and cortisol levels.
• In infants with suspected hypopituitarism, growth hormone and cortisol levels can be measured after glucagon stimulation.
• In infants with suspected hypopituitarism, measure total and free thyroxine (T4) levels to check for hypothyroidism. Thyrotropin-stimulating hormone (TSH) levels are low in secondary and tertiary hypothyroidism. Of interest, these children rarely have positive screen results for hypothyroidism in the newborn period.

Imaging Studies

• In situations of genital ambiguity, pelvic ultrasonography is often helpful. The presence of a uterus and ovaries strongly suggests a virilized female (46,XX) infant.
• When hypopituitarism is suspected, an MRI of the head should be obtained to evaluate the hypothalamic and pituitary areas. In Kallmann syndrome, abnormalities of the olfactory system may be seen.

Other Tests

• A GnRH-stimulation test can be performed to evaluate the pituitary gland's ability to respond and produce LH and FSH.
• Testosterone therapy (testosterone enanthate or cypionate 25-50 mg every month for 3-6 mo) has diagnostic and therapeutic implications. No appreciable increase in penis size (<0.9 cm) with androgen therapy suggests androgen insensitivity.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

• Testosterone therapy in the form of 3-6 monthly intramuscular (IM) injections has been used to increase penis size in infants and children.
• Testosterone therapy has generally been found effective in treating micropenis due to testosterone deficiency.
• • In 1999, Bin-Abbas et al showed that 1 or 2 courses of 3 testosterone injections (25-50 mg) administered at 4-week intervals in infancy or childhood resulted in sufficient increase in penis sizes to reach the reference range for age.³
  • With appropriate pubertal and adult replacement, patients achieved normal adult penis size and reported sexual activity and appropriate gender identity.
• Infants with other hormonal deficiencies (growth hormone deficiency, hypothyroidism, adrenal insufficiency) should receive appropriate hormonal replacements.

Surgical Care

• Gender reassignment with appropriate genitoplasty has been performed. Because most boys with micropenis and descended testes are sensitive to testosterone therapy, consider genitoplasty only in extreme situations in which testosterone insensitivity is demonstrated. Even then, some authors question the wisdom of gender reassignment.
• Circumcision should be avoided, or at least delayed, until appropriate evaluation, gender assignment, and therapy are completed. If associated with penile growth, testosterone therapy may facilitate the circumcision (see Medical Care).

Consultations

• As soon as an infant is discovered to have micropenis, a pediatric endocrinologist should be consulted.
• In some cases, the involvement of a pediatric urologist can also be helpful.
• Psychological support and social services assistance may be useful.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Testosterone therapy has been shown to increase phallus size in infants with micropenis.

Drug Category: Androgenic hormones

Testosterone is the main androgenic hormone predominantly formed in the interstitial (Leydig) cells of the testes. In target tissues, it is converted to the more active form (DHT) by 5-alpha reductase. Testosterone controls the development and maintenance of the male sex organs and the male secondary sex characteristics. It also produces systemic anabolic effects to include increased erythropoietin, increased protein production, and increased retention of calcium. Testosterone is a schedule C-III controlled substance.

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Inpatient Care

• In the newborn nursery, any infant with microphallus should be closely monitored for hypoglycemia.

Further Outpatient Care

• Monitor infants with isolated micropenis for subsequent growth and development problems. If any problems arise, evaluate and treat appropriately.
• Many children with micropenis, especially those with gonadotropin deficiency, do not have spontaneous or complete puberty. In these cases, testosterone is used to initiate puberty, with the dosage gradually increased to an adult replacement dose in a manner that mimics natural puberty.
• In those with hypogonadotropic hypogonadism who desire fertility, hCG and recombinant FSH can be given to promote testosterone secretion and spermatogenesis at the appropriate time by a specialist in reproductive medicine.
• Appropriate counseling should be provided.

Prognosis

• The prognosis of boys with micropenis secondary to gonadotropin or testosterone deficiency is usually good. These individuals generally respond well to testosterone therapy and function normally as adults. However, despite the potential for near-normal adult phallic size and sensitivity, infertility is generally expected.
• Prognosis is much more guarded in children with androgen insensitivity, especially with significant genital ambiguity

Patient Education

• Provide parents with a clear picture of the cause of their child's problems, including expectations from treatment. In situations in which gender assignment is being contemplated, include the parents in the decision process.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• The importance of appropriate gender assignment cannot be overemphasized.
• Evaluate any genital abnormality carefully and early on, using appropriate consultations.
• • Girls with congenital adrenal hyperplasia have been labeled boys prematurely based on the appearance of their genitalia.
  • Some males have been gender assigned as girls and put through genital surgery when androgen therapy may have been a simpler and more appropriate treatment.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Tuladhar R, Davis PG, Batch J. Establishment of a normal range of penile length in preterm infants. J Paediatr Child Health. Oct 1998;34(5):471-3. [Medline].
2. Robertson J, Shilkofski N. Mean Stretched Penile Length. The Harriet Lane Handbook. 2005;277.
3. Bin-Abbas B, Conte FA, Grumbach MM. Congenital hypogonadotropic hypogonadism and micropenis: effect of testosterone treatment on adult penile size why sex reversal is not indicated. J Pediatr. May 1999;134(5):579-83. [Medline].
4. Achermann JC, Hughes IA. Disorders of Sex Development. In: Kronenberg. Williams Textbook of Endocrinology. 11^th ed. Philadelphia, PA: Saunders Elsevier; 2008:Chapter 22.
5. Achermann JC, Ozisik G, Meeks JJ. Genetic causes of human reproductive disease. J Clin Endocrinol Metab. 2002;87:2447-2454. [Medline].
6. Arrigo T, De Luca F, Maghnie M. Relationships between neuroradiological and clinical features in apparently idiopathic hypopituitarism. Eur J Endocrinol. Jul 1998;139(1):84-8. [Medline].
7. Boehmer AL, Brinkmann AO, Sandkuijl LA, et al. 17Beta-hydroxysteroid dehydrogenase-3 deficiency: diagnosis, phenotypic variability, population genetics, and worldwide distribution of ancient and de novo mutations. J Clin Endocrinol Metab. Dec 1999;84(12):4713-21. [Medline].
8. Bourgeois MJ, Jones B, Waagner DC. Micropenis and congenital adrenal hypoplasia. Am J Perinatol. Jan 1989;6(1):69-71. [Medline].
9. Brinkmann A, Jenster G, Ris-Stalpers C. Molecular basis of androgen insensitivity. Steroids. Apr 1996;61(4):172-5. [Medline].
10. Calikoglu AS. Should boys with micropenis be reared as girls? [editorial]. J Pediatr. May 1999;134(5):537-8. [Medline].
11. Danon M, Friedman SC. Ambiguous genitalia, micropenis, hypospadias, and cryptorchidism. In: Pediatric Endocrinology. 3rd ed. Philadelphia, Pa:. WB Saunders;1996:297-301.
12. Dissaneevate P, Warne GL, Zacharin MR. Clinical evaluation in isolated hypogonadotrophic hypogonadism (Kallmann syndrome). J Pediatr Endocrinol Metab. Sep-Oct 1998;11(5):631-8. [Medline].
13. Drugs: Testosterone. MD Consult. Available at www.mdconsult.com. Accessed 15 May 2008.
14. Feldman KW, Smith DW. Fetal phallic growth and penile standards for newborn male infants. J Pediatr. Mar 1975;86(3):395-8. [Medline].
15. Gad YZ, Nasr H, Mazen I. 5 alpha-reductase deficiency in patients with micropenis. J Inherit Metab Dis. Mar 1997;20(1):95-101. [Medline].
16. Grumbach MM. A window of opportunity: the diagnosis of gonadotropin deficiency in the male infant. J Clin Endocrinol Metab. May 2005;90(5):3122-7. [Medline].
17. Hamilton J, Blaser S, Daneman D. MR imaging in idiopathic growth hormone deficiency. AJNR Am J Neuroradiol. Oct 1998;19(9):1609-15. [Medline].
18. Hartke DM, Palmer JS. Anomalies of the penis. J Men's Health Gend. Sept 2006;3(3):244-249.
19. Hayes FJ, Seminara SB, Crowley WF. Hypogonadotropic hypogonadism. Endocrinol Metab Clin North Am. 1998;27:739-763. [Medline].
20. Lee YS, Kirk JM, Stanhope RG, et al. Phenotypic variability in 17beta-hydroxysteroid dehydrogenase-3 deficiency and diagnostic pitfalls. Clin Endocrinol (Oxf). Jul 2007;67(1):20-8. [Medline].
21. Melmed S, Kleinberg D. Anterior Pituitary. In: Kronenberg. Williams Textbook of Endocrinology. 11^th ed. Philadelphia, PA: Saunders Elsevier; 2008:Chapter 8.
22. Palmer JS. Genitourinary manifestations in boys and girls associated with genetic disease. J Men's Health Gend. March 2006;3(1):71-79.
23. Quigley CA. Editorial: The postnatal gonadotropin and sex steroid surge - Insights from the androgen insensitivity syndrome. J Clin Endocrinol Metab. 2002;87:24-28. [Medline].
24. Ragan DC, Casale AJ, Rink RC. Genitourinary anomalies in the CHARGE association. J Urol. Feb 1999;161(2):622-5. [Medline].
25. Schonfeld WA, Beebe GW. Normal growth and variation in male genitalia from birth to maturity. J Urol. 1942;64:759-777.
26. Sinnecker GH, Hiort O, Dibbelt L. Phenotypic classification of male pseudohermaphroditism due to steroid 5 alpha-reductase 2 deficiency. Am J Med Genet. May 3 1996;63(1):223-30. [Medline].
27. Styne DM, Grumbach MM. Puberty: Ontogeny, Neuroendocrinology, Physiology, and Disorders. In: Kronenberg. Williams Textbook of Endocrinology. 11^th ed. Philadelphia, PA: Saunders Elsevier; 2008:Chapter 24.
28. Toogood AA, Stewart PM. Hypopituitarism: clinical features, diagnosis, and management. Endocrinol Metab Clin North Am. Mar 2008;37(1):235-61, x. [Medline].
29. Tsigos C, Latronico C, Chrousos GP. Luteinizing hormone resistance syndromes. Ann N Y Acad Sci. Jun 17 1997;816:263-73. [Medline].
30. Wessells H, Lue TF, McAninch JW. Penile length in the flaccid and erect states: guidelines for penile augmentation. J Urol. Sep 1996;156(3):995-7. [Medline].

Article Last Updated: Jul 9, 2008