doi:10.1016/j.pedhc.2009.05.001
Copyright © 2009 National Association of Pediatric Nurse Practitioners Published
by Mosby, Inc.
Original Article
When Size Matters: A Clinical Review of Pathological Micropenis
Shirley Tsang MS, RN, CPNP,
Available online 23 July 2009.
Abstract
Micropenis is a significantly small penis with normal internal male genitalia.
Micropenis is usually diagnosed shortly after birth, and the cause should be
established; in addition, it should be differentiated from other associated
syndromes. The role of the pediatric nurse practitioner is to diagnose the
micropenis, guide the parents through the options of management, and support all
involved through the selected treatment, whether hormonal or surgical. Patients
affected with micropenis will need long-term management from their pediatric
nurse practitioners, as well as follow-up by endocrinologists, urologists,
pediatric surgeons (if surgery is chosen as the treatment), psychologists, and
social workers. The need of more long-term research on patients with micropenis
also is discussed.
Key words: Micropenis; hypogonadotropic hypogonadism; androgen insensitivity; 5
alpha reductase deficiency; testosterone treatment
Article Outline
Criteria for review
Normal development
Diagnostic criteria
Measurement
Pathophysiology
Hypogonadotropic Hypogonadism
Androgen Insensitivity
5-Alpha Reductase Deficiency
Diagnostic work-up
Treatment
Testosterone Therapy
Topical 5α-dihydrotestosterone Gel
Luteinizing Hormone/Follicle-stimulating Hormone
Surgical Options
Gender reassignment
The role of the pediatric nurse practitioner
Future research
Conclusion
Acknowledgements
References
Vitae
The human body can vary greatly in both shape and size, but the size of certain
body parts may signal an underlying pathology, one example being an extremely
small penis. Micropenis refers to an abnormally small, normally structured penis
with a stretched penile length of less than 2.5 standard deviations (SD) below
the mean for age or stage of sexual development (Zenaty et al., 2006). Patients
who have micropenis have a 46 X,Y karyotyping with gonads that are exclusively
testicular without any signs of hypospadias (Vogt, 2006). Micropenis can be
considered a clinical sign of a larger syndrome or an independent anomaly. One
epidemiological study showed that 1.5 per 10,000 infant males were born with
micropenis between 1997 and 2000 in the United States (Nelson et al., 2005).
Another similar term is "microphallus," which refers to ambiguous-looking
genitalia, but for the purpose of this article we will solely discuss the
subject of micropenis.
The purpose of this article is to familiarize the medical professional, more
specifically the pediatric nurse practitioner (PNP), with the phenomenon of
micropenis and to review normal penile development, as well as the diagnostic
criteria, causes, and treatments for micropenis. Long-term effects in terms of
treatment and gender role also are discussed, along with the important role of
the PNP in caring for affected patients. This article aims to provide PNPs with
insights on this condition and information on management, including necessary
referrals and treatments.
Criteria for review
The studies chosen for review were limited to recent articles and books from
1997 to 2008 and dealt with all aspects involving micropenis. The exception to
these criteria was the article "Micropenis. I. Criteria, Etiologies and
Classification" by Lee et al. (1980), which was published in 1970 and is
considered one of the "gold standards" on micropenis. The search was completed
using Ovid Medline 1950 to 2007 and PubMED, as well as the Augustus C. Long
Health Sciences Library at Columbia University and D. Samuel Gottesman Library
at Albert Einstein College of Medicine of Yeshiva University. Key words used in
the search were "micropenis," "5-alpha reductase deficiency," hypogonadism,"
"androgen insensitivity," and "ambiguous genitalia." The criteria focused on
classifications, causes, management, treatments, and future outcomes of patients
with micropenis.
Normal development
Human male sexual differentiation begins with the sex determination (testis
development) and is followed by sex differentiation (genital development)
(Sultan et al., 2001). Normal sexual differentiation begins the seventh week of
gestation when the fetus contains both the male and female genital ducts. In
normal male differentiation, the sex-determining region of the Y region (SRY)
directs the development of testes, and in the absence of the SRY gene, ovaries
will be formed.
Early in gestation, placental human chorionic gonadotropin stimulates the
developing testes to produce androgens, and by the fifteenth week, the
regulation of androgen secretion is taken over by gonadotropins (luteinizing
hormones and follicle-stimulating hormones) from the fetal pituitary, which is
regulated by the fetal hypothalamus to form the hypothalamic pituitary-gonadal
axis. The androgens produced are Mόllerian inhibitory substance, which cause the
female internal genital structures to regress, and 5α-dihydrotestosterone
(DHT), which is required for the development of male internal genital structures
and the differentiation of male external genitalia (Byne, 2006).
Activation of androgen receptors by testosterone or DHT also appears to
contribute to the masculinization of brain structure and function in some
species. Fetal androgen levels in males are elevated between weeks 8 to 24 of
gestation, with peak levels occurring between weeks 14 to 16, while postnatal
male testosterone levels increase from birth to a peak at 1 to 3 months and then
decrease to prepubertal levels by 4 to 6 months (Byne, 2006). It has been found
that the highest penile growth velocity is associated with the increased levels
of testosterone during the 0- to 3-month period after birth. Thus the postnatal
surge in reproductive hormones appears to be important for genital growth (Boas
et al., 2006). Without satisfactory hypothalamic or pituitary function,
inadequate penile growth will occur despite a normally shaped penis. Similarly,
a primary testicular disorder that causes insufficient testosterone production
near the end of gestation also can result in minimal penile growth (Vogt, 2006).
Diagnostic criteria
The early diagnosis of "true micropenis" is essential and can give practitioners
and parents an early opportunity for various treatment options. The first step
to diagnosing micropenis is a physical examination of the external genitalia of
the patient. Micropenis is by definition a condition that solely affects XY
males, characterized by a small penis with a median raphe, foreskin, and glans
in which the urethral meatus is normally placed, that is, no hypospadias (Figure
1). It may be either retracted or pendulous depending upon the length of the
shaft and may or may not be erectile depending upon the presence or absence of
the corpora cavernosa and corpus spongiosum. The scrotum is present and normally
fused but may be underdeveloped, and the testes typically are descended and may
or may not be normal in function (Lee et al., 1980). In general, there should
not be any signs of feminization.
Full-size image (26K)
Figure 1. A, Micropenis in an infant. (From Morales, S., Guerra, G., Jr., &
Maciel-Cuerra, A. T. (2006). Female counterpart of shawl scrotum in
Aarskog-Scott syndrome. International Brazilian Journal of Urology, 32, 460.
Copyright 2006 by the International Brazilian Journal of Urology. Reprinted with
permission). B, Micropenis in an adult. (From Micropenis. Wikipedia the Free
Encyclopedia. Accessed July 14, 2009, from
http://en.wikipedia.org/wiki/Micropenis.) Figure 1B can be viewed in color
online at www.jpedhc.org.
View Within Article
Occasionally older boys are evaluated for small genitalia due to parental
concern. However, these boys usually are prepubertal and obese, and the minimal
size of their penis is a result of the penis being hidden in the prepubic fat.
The size of their penis is warranted as normal unless the size falls within the
micropenis criteria. An accurate penile length measurement and thorough physical
assessment can distinguish micropenis from other conditions (Vogt, 2006).
Misdiagnosing this condition may delay treatment and cause more frustration for
the parents.
Measurement
Getting the correct penile measurement is very important because a diagnosis of
micropenis really hinges on the size. An accurate measurement that correlates
with the requirement of 2.5 SD below the norm for age plus external and internal
organs of an XY karyotype can be sufficient evidence to support a diagnosis of
micropenis.
The conventional method for measuring the penis is using a ruler or calipers.
The penile length should be the fully stretched rather than flaccid and can be
achieved by grasping the glans between the thumb and forefinger and measuring
from the pubic ramus, along the dorsum, to the tip of the glans penis. The
suprapubic fat pad should be compressed in as completely as possible and the
foreskin, if present, is not included in the measurement (Lee et al., 1980).
Another option is using a 10-mL disposable syringe in a modified construction.
The needle-bearing end is removed and the piston is inserted in to the cut end
(Figure 2). The flanged end is then placed over the penis, firmly pressing in to
the fat pad while the piston is withdrawn, causing the penis to be suctioned
into the injector. Once the penis is stretched out within the syringe during
optimal suction, the penis length is read from the attached scale. Using this
method eliminates measurement variability caused by the suprapubic fat pad by
gently pressing the syringe on to the symphysis pubis (Ozbey, Temiz, & Salman,
1999).
Full-size image (12K)
Figure 2. Modified syringe used to measure the penis. This figure can be viewed
in color online at www.jpedhc.org.
View Within Article
After obtaining a correct measurement of the penis, the value is compared with
the normal size range for chronological age. The penis must measure less than
2.5 SD below the mean for age to qualify as micropenis. Table 1 contains the
average stretched penile length (in centimeters) of normal male subjects based
on age and the length 2.5 SD below. For premature newborns, the following
formula describes the expected penile length for infants born between 24 and 36
weeks gestation:
Table 1.
Stretched penile length in normal male subjects (cm)
Age Mean Mean 2.5 SD
Newborn: 30 wk 2.5 ± 0.4 1.5
Newborn: 34 wk 3.0 ± 0.4 2.0
Newborn: term 3.2 ± 0.4 2.5-2.4
0-5 mo 3.9 ± 0.8 1.9
6-12 mo 4.3 ± 0.8 2.3
1-2 y 4.7 ± 0.8 2.6
2-3 y 5.1 ± 0.9 2.9
3-4 y 5.5 ± 0.9 3.3
4-5 y 5.7 ± 0.9 3.5
5-6 y 6.0 ± 0.9 3.8
6-7 y 6.1 ± 0.9 3.9
7-8 y 6.2 ± 1.0 3.7
8-9 y 6.3 ± 1.0 3.8
9-10 y 6.3 ± 1.0 3.8
10-11 y 6.4 ± 1.1 3.7
Adult 13.3 ± 1.6 9.3
Full-size table
This table was published in Endocrinology, Volume, Custer, J., & Rau, R., The
Harriet Lane handbook, 18th ed., 269-300, Copyright Elsevier (2009).
View Within Article
Expected penile length (cm) = 2.27 + 0.16 X (gestational age in weeks)
In general, full-term newborns must achieve a measurement of less than 2.5 cm,
or 1 inch, to meet the definition of micropenis (Vogt, 2006). A penile length
that falls into the micropenis category warrants further evaluation of cause and
treatment (Table 1).
Other syndromes can also be mistaken for micropenis, such as concealed penises
(Figure 3) which are further categorized as buried penis, trapped penis, and
webbed penis. A buried penis is a typical-sized penis enclosed in the suprapubic
fat pad because of a lack of skin attachment to the shaft, while the trapped
penis results from excessive circumcision where adhesions form between the
scrotal and penile skin. A webbed penis is characterized by the skin of the
shaft being tethered to the ventral surface of the scrotum (Borsellino,
Spagnoli, Vallasciani, Martini, & Ferro, 2007). Additional differential
diagnoses are penile agenesis, where there is no penis at all, or penis with
marked chordee, when the head of the penis is curved downward (Menon & Khatwa,
2000).
Full-size image (33K)
Figure 3. Examples of concealed penises. (Reprinted from Urology, 69,
Borsellino, A., Spagnoli, A., Vallasciani, S., Martini, L., & Ferro, F, Surgical
approach to concealed penis: Technical refinements and outcome, 1196, Copyright
(2007) with permission from Elsevier.) This figure can be viewed in color online
at www.jpedhc.org.
View Within Article
Pathophysiology
Micropenis can occur as an isolated incident or in association with other
conditions, especially those involving hormone deficiencies. Some etiological
factors of micropenis due to hormone deficiencies are hypogonadotropic
hypogonadism resulting from an endocrine anomaly of the
hypothalamic-pituitary-gonadal axis and androgen insensitivity syndrome with
inadequate penile growth despite normal or excessive androgen secretion
([Ludwig, 1999] and [Menon and Khatwa, 2000]). Other possible causes of
gonadotropin deficiency are caused by hypothalamic dysfunction, such as
Kallmann's syndrome or Prader-Willi syndrome. There also can be decreased
synthesis of testosterone or conversion of testosterone to DHT, as is the case
of 5-alpha reductase deficiency (5αRD), decreased testosterone sensitivity,
and growth hormone deficiency. Table 2 describes in more detail the
pathophysiology, clinical findings, and diagnostic work-up results of
hypogonadotropic hypogonadism, androgen insensitivity, and 5αRD, while Box
1 lists other conditions associated with micropenis.
Table 2.
Hypogonadotropic hypogonadism, androgen insensitivity, and 5α reductase
deficiency
Differential Pathophysiology Clinical findings Diagnostic work-up
Hypogonadotropic hypogonadism (idiopathic or Kallman's syndrome) Failure of the
hypothalamus to secrete gonadotropin releasing hormones Idiopathic can present
with micropenis; Kallman's syndrome: micropenis or cryptorchidism, anosomia,
hyposomia, sensorineural deafness, visual abnormalities, cleft lip and palate,
congenital heart disease, renal agenesis, cerebellar ataxia, arm span greater
than height, short metatarsals 1. Demonstration of prepubertal serum
testosterone concentrations of less than 100 ng/dL in males
2. Low or normal serum LH and FSH concentrations (usually less than 4 to 5 IU/L)
3. Otherwise normal anterior pituitary function
4. Normal appearance of the hypothalamus and pituitary region on MRI
Androgen insensitivity (complete or partial) Defective mechanism of action of
the androgen on target cell or defective androgen receptor gene (loss-of-
function); caused by defects in gene coding, environmental chemicals that impair
DHT synthesis, and AR mediation Micropenis or ambiguous genitalia;CAIS: female
external genitalia with normal labia, clitoris, and vaginal canal; PAIS: wide
range, female with only clitoromegaly or male with micropenis and/or hypospadias
1. Karyotyping, chromosomally male or female
2. Normal or abnormal serum testosterone levels
3. Mutations on the coding region for AR seen upon sequencing
5α reductase deficiency Mutations in the steroid 5α-reductase type 2
gene causing a lack of enzyme production or defects in androgen receptor site
Isolated micropenis or hypospadias, severe ambiguity of external genitalia;
internal male genitalia are normally developed 1. Increased ratio of serum
testosterone to DHT
2. DHT level is low to undetectable
3. Testosterone level is normal to moderately elevated
4. Molecular analysis of 5αR type 2 gene (not commercially available)
Full-size table
From [Bertelloni et al., 2007], [Fechner et al., 2008], [Galani et al., 2008],
[Lee et al., 1980], [Ludwig, 1999], [Menon and Khatwa, 2000], [Sultan et al.,
2001], [Vogt, 2006] and [Wisniewski and Migeon, 2002].
AR, androgen receptor; CAIS, complete androgen insensitivity syndrome; DHT,
5α-dihydrotestosterone; FSH, follicle-stimulating hormone; LH, luteinizing
hormone; MRI, magnetic resonance imaging; PAIS, partial androgen insensitivity
syndrome.
View Within Article
Box 1. Conditions associated with micropenis
Hypogonadotropic hypogonadism
Kallmann
Klinefelter
Prader-Willi
Bardet-Biedl
Rud
Septo-optic dysplasia
Robinow
Partial androgen insensitivity
Deficiency of 5α reductase
Decreased testosterone production
Growth hormone deficiency
Panhypopituitarism
Other
CHARGE
Noonan
From Lee et al., 1980, and Ludwig, 1999.
Hypogonadotropic Hypogonadism
Hypogonadotropic hypogonadism can present initially with micropenis, which
allows it to be diagnosed shortly after birth (Main, Schmidt, Toppari, &
Skakkebaek, 2002). Hypogonadotropic hypogonadism is the failure of the
hypothalamus to secrete gonadotropin-releasing hormones (GnRH) that normally
stimulate the pituitary gland to secrete the gonadotropins luteinizing hormone
(LH) and follicle-stimulating hormone (FSH), which stimulate male testes to
secrete hormones that are responsible for normal pubertal maturation and
reproductive function (de Roux et al., 2003). The hypothalamic-pituitary
function is otherwise normal in most patients, and hypothalamic-pituitary
imaging reveals no space-occupying lesions. This condition can be idiopathic or
a result of Kallman's syndrome (Fechner, Fong, & McGovern, 2008). In Kallman's
syndrome, the failure of the hypothalamus to secrete GnRH leaves a deficiency in
sex hormones that presents with micropenis or cryptorchidism and anosmia (a lack
of smell) and hyposomia (inadequate development of the body). Kallman's syndrome
is an autosomal dominant, autosomal recessive or X-linked recessive disease and
can be distinguished from idiopathic hypogonadotropic hypogonadism with an
objective smell test to document anosmia (Fechner et al.). The syndrome is
diagnosed on the basis of clinical presentation, while the GnRH deficiency is
diagnosed biochemically.
Androgen Insensitivity
In complete androgen insensitivity syndrome (CAIS) and partial androgen
insensitivity syndrome (PAIS), the mechanism of the androgen action on the
target cell is defective, or in other words, there is a loss-of-function
mutation in the androgen receptor gene ([Menon and Khatwa, 2000] and [Wisniewski
and Migeon, 2002]). This x-linked recessive condition can result in micropenis
or genitalia that are more uncertain (Kohler et al., 2005). Individuals with
CAIS and PAIS are chromosomally and gonadally male; however, those with CAIS
have female external genitalia with a normal labia, clitoris, and vaginal canal,
while PAIS external genitalia can range from slightly virilized female to
slightly undervirilized male. For the purpose of this article, we will be
focusing on PAIS, although diagnostic screening would be the same for both. Male
subjects affected with PAIS have normal testes, most likely undistended, with
normal production of testosterone and normal conversion to DHT, and because they
produce normal amounts of Mόllerian inhibitory substance, they do not have
fallopian tubes, a uterus, or a vagina. They also may or may not have normal
serum testosterone levels because they only have partial enzyme defects (Galani,
Kitsiou-Tzeli, Sofokleous, Kanavakis, & Kalpini-Mavrou, 2008).
5-Alpha Reductase Deficiency
Peripheral conversion of testosterone into DHT by enzyme 5αR is shown to
play a major role in the masculine differentiation of the external genitalia and
the subsequent phallic growth (Gad, Nasr, Mazen, Salah, & El-Ridi, 1997).
5αRD is primarily due to mutations leading to lack of enzyme production,
but it also can be caused by defects in the androgen receptor site. Patients
affected with 5αRD are genetically male, but some patients are mistakenly
assigned as female because of under-virilization and are raised as such.
However, during puberty a variable degree of virilization will occur because of
the increased surge of testosterone, and a change in gender may be needed
(Bertelloni et al., 2007). It has been questioned as to how much a role
5αRD plays in a male subject with congenital micropenis. In the study by
Gad and colleagues, it was found that 5αRD played a minimal role in
isolated micropenis and was more prevalent in cases of ambiguous genitalia with
micropenis; however, the study also found that 5αRD did correlate with
penile length in intersex cases. If 5αRD is not the main cause of
micropenis, it does seem to play a part in the growth of a penis.
Diagnostic work-up
The initial step of treatment of micropenis is to have a complete work-up
ordered by the primary care provider or endocrinologist, including chromosomal
analysis or karyotyping with Y fluorescence to determine the genetic sex and to
rule out other syndromes (Menon & Khatwa, 2000). Levels of serum gonadotropin
(LH and FSH), testosterone, DHT, and androstenedione (a precursor sex hormone)
also are measured (Table 3). The gonadotropin levels will be able to narrow down
the differential diagnoses, while testosterone and DHT levels can determine the
testes' responsiveness to gonadotropin stimulation. It also can be used to
diagnose 5αRD. A GnRH stimulation test will evaluate the pituitary gland's
ability to respond and produce LH and FSH. Levels of the growth hormone
cortisol, as well as total and free thyroxine levels, will determine
hypopituitarism, and a human chorionic gonadotropin stimulation test will
measure the body's ability to perform testosterone biosynthesis ([Custer and
Rau, 2009] and [Lee et al., 1980]). Imaging studies such as pelvic
ultrasonography can be helpful in cases of ambiguous genitalia to visualize the
internal reproductive organs, or a magnetic resonance imaging scan of the head
can be used to assess the pituitary and hypothalamic area (Vogt, 2006).
Table 3.
Normal serum levels of hormones
Gonadotropins
Age FSH (mIU/mL) LH (mIU/mL)
Prepubertal children 0.0-2.8 0.0-1.6
Men 1.4-14.4
Women, follicular phase 3.7-12.9
Testosterone
Age Testosterone (ng/dL)
Prepubertal children 10-20
Men 275-875
Women 23-75
Pregnancy 35-195
Dihydrotestosterone
Age Males (ng/dL) Females (ng/dL)
Cord blood <2-8 <2-5
1-6 mo 12-85 <5
Prepubertal <5 <5
Tanner stage II-III 3-33 5-19
Tanner stage IV-V 22-75 3-30
Androstenedione
Age Males (ng/dL) Females (ng/dL)
Pre-term infants
26-28 wk to day 4 of life 92-892 92-892
31-35 wk to day 4 of life 80-446 80-446
Full-term infants
1-7 day 20-290 20-290
1-12 mo 6-68 6-68
Prepubertal children 8-50 8-50
Tanner II 31-65 42-100
Tanner III 50-100 80-190
Tanner IV 48-140 77-225
Tanner V 65-210 80-240
Adults 78-205 85-275
Full-size table
This table was published in Endocrinology, Volume, Custer, J., & Rau, R., The
Harriet Lane handbook, 18th ed., 269-300, Copyright Elsevier (2009).
FSH, Follicle-stimulating hormone; LH, luteinizing hormone.
View Within Article
Treatment
Testosterone Therapy
Initial treatment is a short course of testosterone to assess the ability of the
penis to respond to the hormone. Treatment can be given via intramuscular
injections or applied topically. Testosterone cypionate or enanthate in oil, 25
mg, is given intramuscularly every 3 weeks for 4 months for the initial course.
The adverse effects are minimal and include temporary accelerated growth
velocity and bone age (Menon & Khatwa, 2000). Topical testosterone application
also has been shown to be effective in young children. Arisaka et al. (2001)
administered 5% testosterone ointment daily to 50 boys aged 5 months to 8 years
for 30 days, which resulted in increased penile length. Transdermally absorbed
testosterone also has been shown to stimulate the secretion of growth hormone
from the pituitary gland, which will increase the production of insulin-like
growth factor-I, a factor that promotes bone growth. Long-term administration
has the potential to enhance growth in penile length as well as skeletal growth
(Arisaka et al.).
Empirical evidence indicates that testosterone treatment has a positive impact
on penile growth during infancy, yet it is unclear whether the growth will
continue during adolescence and adulthood (Baskin et al., 1997). A lack of
response is likely to represent androgen resistance or androgen receptor
deficiency, and therefore failure to virilize at puberty is possible. An
important aspect of testosterone treatment is the recommendation to begin
treatment early in infancy and childhood. Patients with hypogonadotropic
hypogonadism show a decrease in penile androgen expression. There is a natural
decrease in androgen receptors in early adulthood, and so the early
administration of testosterone allows for increased penile androgen receptor
concentration and duration during the period before this decline (Menon &
Khatwa, 2000).
Topical 5α-dihydrotestosterone Gel
In prepubertal patients with androgen insensitive syndrome, topical DHT gel
applied to the peri-scrotal region three times a day for 5 weeks raised serum
DHT. In a study by Ong, Wong, and Yong (1999), the aforementioned treatment
resulted in increased penile length and improved male genital development in a
46 X,Y infant. This treatment also has been shown to work with patients affected
with 5αRD, although the large amount of testosterone produced at puberty
may be enough for complete virilization. In a research study by Bertelloni and
colleagues (2007), three Italian 46 X,Y newborns, two with 5αRD, were given
a trial of DHT cream, which resulted in an increase of penile length of at least
120%. In a study by Charmandari, Dattania, Perry, Hindmarsha, and Brooka (2001),
percutaneous 2.5% DHT gel was used on six children (ages 1.9 to 8.3 years)
affected by micropenis of various etiologies. They found that administration of
DHT, 0.2 to 0.3 mg/kg once daily for 3 to 4 months, was able to increase phallic
growth. Adverse effects were minimal, with minor irritation to the skin, and
similar to adverse effects of testosterone treatment (Kaya et al., 2008).
Topical DHT can be a good alternative for patients who do not respond to
testosterone.
Luteinizing Hormone/Follicle-stimulating Hormone
In patients with hypogonadotropic hypogonadism, treatment with recombinant human
LH and FSH during the first year of life has been successful in inducing
testicular growth and a little increase in penile length. In a study by Main and
colleagues (2002), a patient with micropenis was given recombinant human LH and
FSH in doses of 20 and 21.3 IU as subcutaneous injections twice a week over a
period of 6 months and was able to achieve sufficient phallic growth when
testosterone was added to the treatment. Some adverse effects reported included
increased body hair and pigmentation as well as intermittent nausea. In general,
the treatment was well tolerated (Main et al.).
Although exogenous hormone treatments can result in increased penile growth in
the patient with micropenis, penile length still may be below average in
adulthood (Tietjen, Uramoto, Tindall, & Husmann, 1998).
Surgical Options
If the micropenis does not achieve adequate length through medical intervention,
surgical options are available, but these options should only be considered
after all other treatments have been exhausted. One option is surgical
construction of the penis, or elongation plastic surgery. These procedures are
highly complex and carry with them many risks, especially because the patient
most likely will undergo multiple treatments and the results may not produce
acceptable functional or cosmetic outcomes (Byne, 2006). Genitoplasty also can
have other complications such as increased scarring, pain, and decreased sexual
pleasure. These complex procedures requires a skilled team of physicians,
including plastic surgeons, microvascular surgeons, and urologists, and
currently they are being performed only in highly specialized centers that can
guarantee high standard outcomes (De Castro, Merlini, Rigamonti, & Macedo,
2006). However, social and psychological concerns justify early palliative
phalloplasty.
Gender reassignment
Gender reassignment was once a popular option because prompt surgical
normalization of external genital anomalies was viewed as necessary to establish
the perceived gender versus chromosomal gender (Byne, 2006). However, recent
reports in long-term follow-up have shown that the majority of male patients
with penile malformation who are raised as girls have demonstrated a marked
male-typical shift in psychosocial and psychosexual development, with most
declaring themselves to be male (De Castro et al., 2006). This information
provided by adults with micropenis who claim a male gender role, have a
heterosexual orientation, and indicate a steadfast male gender identity has led
to a change in attitude regarding gender reassignment. Furthermore, information
concerning the impact of androgen on the fetal brain suggests that sex steroid
exposure may have an organizing influence on gender, particularly in regard to
gender role (Lee & Houk, 2004). More recent reports suggest that biological
factors in the prenatal period also may have a significant role in gender
identification, especially due to brain imprinting from testosterone. On the
other hand, long-term psychosexual issues may occur in the presence of a small
sex organ (Gearhart, Rink, & Mouriquand, 2001). Although gender reassignment is
now discouraged, there are problems revolving around psychological concerns.
Some concerns include patients expressing that their quality of life had been
negatively affected by the presence of micropenis and seeking psychological
counseling because of concerns of sexual inadequacy and/or depression. A high
incidence of depression combined with the patients' perception that their
micropenis has negatively affected their quality of life indicates that
psychological counseling should be recommended routinely in the treatment of
these patients (Canning, 2006).
The role of the pediatric nurse practitioner
The first health care professional to discover the anomaly is most likely the
pediatrician or PNP during the newborn examination or a well-infant check-up
during the first year of life. The first step in diagnosing suspected micropenis
is to confirm that the length of the penis fits within the criteria of a
diagnosis of micropenis. Measuring should be done on the stretched penile length
using one of the two methods previously described, either the ruler or syringe.
The PNP making the diagnosis should be familiar with the genetic and
endocrinology principles that direct fetal sex differentiation as well as the
influence of fetal sex hormones on gender identity (Stein, Sandberg, Mazur,
Eugster, & Daaboul, 2004). This knowledge enables the PNP to explain to parents
how hormones affect penile growth and to provide basic information regarding
their child's condition. Next, the PNP should refer the patient to a pediatric
endocrinologist for consultation and more in-depth information on the condition.
The laboratory studies needed to confirm the diagnosis can be ordered either by
the PNP or the endocrinologist.
Once the work-up on the patient is complete and the endocrinologist involved in
the child's care has determined the cause of the micropenis, treatment and
management can begin. The person responsible for providing the parents with the
diagnostic and prognostic information must present all the information gathered
during the evaluation, as well as the pros and cons of each treatment option
(Lee et al., 1980). The initial treatment is testosterone therapy to increase
the size of the penis. This therapy can initiated by the endocrinologist and
followed up with the PNP, with a re-evaluation with the endocrinologist at the
end of the treatment. If the therapy is able to achieve adequate growth,
treatment is considered a success, although it is uncertain whether growth is
maintained into adulthood (Menon & Khatwa, 2000).
If the testosterone course fails in adding length, the other hormonal treatments
described in the treatment section can be administered. If all the hormonal
treatments fail, the PNP may provide the parents with information on surgical
options, such as penile reconstruction or sex reassignment, and a referral to a
pediatric surgeon or pediatric urology surgeon. The surgical options include the
technically difficult phalloplasty or the easier vaginoplasty, and each
procedure is associated with short- and long-term complications (Stein et al.,
2004 M. Stein, D. Sandberg, T. Mazur, E. Eugster and J. Daaboul, A newborn
infant with a disorder of sexual differentiation, Pediatrics 114 (2004), pp.
14731476.Stein et al., 2004).
If the parents decide to forgo surgery, and the PNP must devise a management
plan to help the patient adjust to life as a male with micropenis.
In all cases, psychological counseling and social services are helpful and most
likely necessary to both the patient and the parents and should be started early
because these patients seem to suffer emotionally (Husmann, 2004). Psychiatric
counseling may be needed as the child grows and deals with his condition. Common
issues among male subjects with micropenis include fear of sexual rejection,
sexual inadequacy, the size of their penis affecting their quality of life, and
poor body image (Husmann). On another note, long-term follow-up in some patients
has shown that there were no major alterations in male sexual activity comfort
or identity (Waldert et al., 2005).
The focus of management has remained fixed on determining which medical and/or
surgical interventions will yield an optimal outcome for the condition. The most
appropriate care has the medical team involving the parents in each step of
decision making along the way. Each set of parents, with their unique
sociocultural beliefs and backgrounds, would make different decisions based on
what their conception of their child's gender is and how they see their child's
future in the context of their family and society (Stein et al., 2004). Parents
must feel convinced that no medical information has been kept from them and that
the decision is done with full knowledge of alternatives with the support of the
PNP and the rest of the medical team.
Long-term follow-up is provided by the PNP within the context of the child'
primary health care setting. The PNP continues to monitor penile length,
maintains the hormone treatments or surgical outcomes, and screens for future
complications. She or he refers the patient as needed to specialty providers and
coordinates the care between the medical team and the patient and family. The
PNP also provides holistic care, which includes emotional support for the
parents during diagnosis and management and for the patient during long-term
follow-up.
Future research
Research into the field of micropenis is needed, because there are not many
long-term follow-up results. Long-term data are needed for patients with
micropenis who underwent hormone therapy or surgical procedures for penile
elongation or gender reassignment to see if the result remained permanent
throughout childhood, adolescence, and adulthood. A comparative study also is
needed to see which hormone treatment has yielded the most continuous results.
Appropriate phalloplasty should be explored as an option for younger children
because of the fact that some children experience significant psychological
disturbance and the current surgical procedures are aimed at the older child or
adult. Overall, more research is needed on which clinical practices are most
likely to achieve the best quality of life for people affected by micropenis.
Conclusion
A boy with a penis measuring 2.5 SD below the norm for age needs to be evaluated
for micropenis. Laboratory studies are done to determine the possible cause and
the best treatment to administer to get best possible outcome. Management of
these pediatric patients can be overseen by their PNP and will involve medical
or surgical treatment, appropriate referrals to an endocrinologist and possibly
a geneticist, psychological counseling, and follow-up throughout childhood. It
is important to counsel the parents of these children every step of the way to
ensure that the best quality of care is given.
I thank Dr. Rita Marie John, Director of the Pediatric Nurse Practitioner
Program at the Columbia University School of Nursing, for her help and advice
while I was writing this article.
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Conflicts of interest: None to report.
Correspondence: Shirley Tsang, MS, RN, CPNP
Vitae
Shirley Tsang, Pediatric Nurse Practitioner, Neighborhood and Family Health
Center, Bronx, NY.
Journal of Pediatric Health Caren Article in Press, Corrected Proof
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