Clinical Features Of Klinefelters Syndrome

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The clinical manifestations of KS are those of prepubertal androgen deficiency and infertility. Because testicular failure occurs before puberty, the developmental changes

Klinefelter Syndrome
Fig. 2. An individual with Klinefelter's syndrome. Note tall body proportions, gynecomastia, relative paucity of facial and body hair, and small testis. (Photos courtesy of Dr. C. Alvin Paulsen.)

of puberty do not progress normally. This leads to the classic phenotype of KS: long legs, with an arm span frequently greater than height, gynecomastia, decreased muscle mass and increased abdominal adiposity, decreased facial and body hair, and small testes—which often measure less than 5 mL in volume (see Fig. 2). The penis may be decreased in size but is often of normal length. Gynecomastia is variable but is often prominent and may require surgical correction. Mosaicism may present more subtly, because affected individuals can appear anywhere along a phenotypic spectrum between classical KS and "normal." Infertility is almost universal; however, human leukocyte antigen (HLA)-confirmed children fathered by individuals with KS have been reported (19). Moreover, assisted reproductive techniques may allow some men with KS to father children (see section on KS and infertility). The frequency of various symptoms and signs of KS is summarized in Table 2.

Hormonally, the majority of affected men have decreased total testosterone levels, and those with normal total testosterone levels may, in fact have decreased free testosterone, because serum sex hormone-binding globulin (SHBG) levels are elevated in KS (18). More than 90% of men have increased levels of serum gonadotropins, particularly FSH, because inhibin-B levels are low in individuals with KS (5). Because of low androgen levels, individuals with KS can have low bone mineral density and are at increased risk of developing osteoporosis, despite seemingly adequate androgen

Table 2

Clinical Characteristics of Men With Klinefelter's Syndrome

Feature %

Infertility 99-100

Small testes 99-100

Elevated gonadotropins 90-100

Low testosterone levels 65-85

Gynecomastia 50-75

Reduced facial and pubic hair 50-80

Reduced penis size 10-25

therapy (20). This may result from the failure to achieve peak bone mass early in life, because testosterone replacement before the age of 20 can improve bone mass to normal levels, whereas testosterone therapy started later in life has a less potent effect (21). As a result, calcium and vitamin D supplementation, as well as baseline densitometry, are probably prudent in individuals with KS, especially those who began androgen therapy later in life.

At one time, individuals with KS were believed to be frequently retarded and/or at increased risk of criminal behavior (22,23). Those studies were often misleading, because they were based on preselected (usually committed or incarcerated) populations; however, such populations were not representative of the syndrome as a whole. Subsequent population-based studies have demonstrated a nonsignificant, but slightly increased, rate of incarceration among individuals with KS. The increased rate of imprisonment is most likely accounted for by a lower average score on IQ tests when compared to controls (24).

When tested, groups of adult individuals with KS do exhibit significant deficits in language-processing skills, including reading and spelling, verbal processing speed, verbal and nonverbal executive abilities, and motor dexterity (25,26). In general, this leads to lower average school performance and an increased frequency of psychological consultation. In addition, adolescent males with KS exhibit lowered sexual activity compared with their peers (27). It is important to remember that individual variation in mental function is marked; some individuals with KS perform well above average on intelligence tests. Moreover, it seems likely that early developmental interventions and language tutoring in boys can assist in preventing disabling difficulties with language skills later in adult life (28,29).

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  • Doroteo
    What is a normal testosterone level with klinefelter's syndrome?
    8 years ago
    What of the clinical features of klinefelter's syndrome?
    8 years ago
  • Anselma Endrizzi
    What are the changes that will occur at puberty?
    8 years ago
  • marigold
    Do i have klinefelters?
    8 years ago
  • thorsten
    How klinefelter's syndrome occurs?
    8 years ago
  • lillian
    Can a klinefelter's syndrome guy have a normal penis?
    7 years ago
  • matthias
    Are individuals with klinefelters syndrome more likely to be obese?
    7 years ago
  • sara
    When do facial features change with klinesfelter?
    7 years ago
  • kerstin
    Do Klinefelter patients have low fish levels?
    7 years ago
  • Iines
    What is the testosterone level in klinefelters?
    7 years ago
  • LISA
    Why testosterone therapy start in puberty age with klinefelter syndrome?
    7 years ago
  • anne
    Can kleinfelter with normal penis?
    7 years ago
  • manuela werner
    What is the level of testosterone in children with klinefelter's syndrome?
    6 years ago
  • janina
    Do kleinfelter patients have normal facial features?
    5 years ago
    Why testicles are tall than penis?
    5 years ago
  • sanna
    Is it true that man who has his body build up has smalll pinis?
    4 years ago
  • sinit
    What causes a small penis?
    4 years ago
  • virginio rossi
    Is it normal to have small testicles?
    4 years ago
  • antonina
    What causes small size of penis?
    4 years ago
  • rosie
    What is the size of the penis klinefelter syndrome?
    3 years ago
  • barbara
    What are the Clinical features of Klein felter?
    3 years ago
  • rosalia
    Why do some guys have small balls?
    3 years ago
  • negassi
    Why penis size reduced in men?
    2 years ago
  • Lidya Alem
    Is it true white guys have small penis?
    2 years ago
  • andreas
    Is it possible for klienfelter a normal testosterone level?
    2 years ago
  • marco
    How small are testicles of a man with klinefelters?
    1 year ago
  • vera
    Why is there low testosterone levels in males with klinefelter syndrome?
    3 months ago
  • anja schuster
    Can you have normal levels if testosterone if you have klinefelters?
    3 months ago
  • iago
    Can mosaic klinefelter have normal testosterone?
    3 months ago

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