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Genetic and Rare Diseases Information Center (GARD)

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Klinefelter syndrome

Other Names for this Disease
  • Klinefelter's syndrome
  • XXY syndrome
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Your Question

My son has Klinefelter syndrome. I am aware that he may need testosterone replacement therapy (TRT) when he reaches puberty. For how long is TRT usually done?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

How might Klinefelter syndrome be treated?

Because symptoms of Klinefelter syndrome (KS) can sometimes be very mild, many individuals are never diagnosed or treated. The type of therapies available for individuals seeking treatment depends on the type of symptoms present. There are conflicting opinions in some of the literature about when treatment should be started and who should be treated. The earlier in life that KS symptoms are recognized and treated (for example, by early puberty), the more likely it is that the symptoms can be reduced or eliminated. However, although the majority of boys with KS grow up to live as males, some reportedly develop atypical gender identities. For these individuals, certain therapies (such as supplemental testosterone) may not be suitable. Gender identity should be discussed with health care providers before starting treatment.[1]

Management options available to individuals with signs and symptoms of Klinefelter syndrome may include:
  • Educational interventions – As children, many individuals with Klinefelter syndrome qualify for special services to help them in school. Teachers can also help by using certain methods in the classroom, such as breaking bigger tasks into small steps.
  • Therapeutic options – A variety of therapists, such as physical, speech, occupational, behavioral, mental health, and family therapists, can often help reduce or eliminate some of the symptoms of Klinefelter syndrome such as poor muscle tone, speech and language problems, or low self-confidence.
  • Medical management – About half of individuals with KS have low testosterone levels, which may be raised by taking supplemental testosterone. Having a more normal testosterone level can help individuals develop bigger muscles, a deeper voice, and facial and body hair. Many healthcare providers recommend testosterone therapy when a boy reaches puberty. However, not all males with KS benefit from testosterone therapy, and this therapy also may not be suitable for some individuals depending on gender identity.[2][1] Some individuals may opt to have breast removal or reduction surgery.[1]
Last updated: 9/20/2013

For how long is testosterone replacement therapy typically used for individuals with Klinefelter syndrome?

About half of individuals with a 47, XXY chromosome finding have low testosterone levels, which can typically be raised by taking supplemental testosterone. However, not all males with a 47, XXY chromosome finding benefit from testosterone therapy. Furthermore, although the majority of individuals with a 47, XXY chromosome finding and/or Klinefelter syndrome grow up to identify as males, some develop atypical gender identities. For these individuals, supplemental testosterone may not be appropriate. Gender identity should be discussed with health care specialists before starting treatment.

In most cases, testosterone replacement therapy (sometimes referred to as androgen therapy), is begun at puberty (around age 12 for males). The dose is usually gradually increased until it is enough to maintain age-appropriate serum concentrations of testosterone, estradiol, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). It is used to raise levels of androgen, increase the development of male characteristics, and it may improve psychosocial status during puberty. Regular testosterone injections can promote strength and facial hair growth; build a more muscular body type; increase sexual desire; enlarge the testes; improve mood, self-image, and behavior; and protect against early osteoporosis.[3]

Limited information about the treatment of adults with Klinefelter syndrome is available; however, research has shown that continued testosterone injections, even if begun in adulthood, can be beneficial to those seeking treatment and may continue to help with hypogonadism, low libido (sex drive), and psychosocial issues.[4][5] Individuals with Klinefelter syndrome should consult their physicians regarding their personal course of treatment and to discuss the risks and benefits of testosterone replacement therapy.
Last updated: 9/18/2013