NOTE: The following information is meant for educational and informational purposes only and is not intended as a tool to diagnose or treat any medical condition.

Klinefelter Syndrome

What is Klinefelter Syndrome?

Klinefelter syndrome (KS), also known as XXY-Syndrome or XXY trisomy, is a genetic condition that occurs in male patients who are born with an extra copy of the X chromosome. It can affect different stages of male development, such as physical appearance, language, and social maturity. It affects about 1 in every 650 newborn boys and is the most common sex chromosome disorder.

Klinefelter syndrome can manifest differently and can even be so mild that it goes undiagnosed until adulthood. It’s believed that up to 75% of affected men and boys are undiagnosed.

Klinefelter Syndrome Symptoms

Signs and symptoms can vary by age. Prior to puberty, boys with Klinefelter syndrome may be taller and may have more fat around their abdomen than other boys their age. After puberty, they may have:

  • Smaller genitals

  • Small, firm testicles or even undescended testes

  • Enlarged male breast tissue (gynecomastia)

  • Reduced facial and body hair

  • Less muscle mass

  • Longer legs, wider hips, and narrower shoulders compared to other boys

  • Bone weakness

  • Lower sexual interest

  • Reduced energy levels

  • Hormonal imbalance

  • Elevated serum estrogen levels

Young men with Klinefelter syndrome may have language or learning problems. Many are shy and quiet and tend to have difficulty interacting socially. In adult males, infertility is the most prominent symptom because of decreased androgen production and gonadal dysfunction.

More than half of men with Klinefelter syndrome have an increased risk of developing metabolic syndrome, as well as serious health concerns like tremors, breast cancer (if they develop gynecomastia or enlarged male breast tissue), osteoporosis, liver disease, kidney disease, and autoimmune disorders.

Klinefelter Syndrome and Testosterone Production

Because males with Klinefelter syndrome have smaller testes, it can be more difficult to produce hormones. This reduced testosterone production can lead to unbalanced hormone levels. Hormone imbalance can cause a variety of effects including delayed puberty and gynecomastia, a condition marked by increased breast tissue growth in one or both breasts.

Diagnosing Klinefelter Syndrome

In addition to a physical examination of the genital area and chest, two other tests are commonly used to diagnose Klinefelter syndrome:

  • Hormone testing: Blood and urine samples are evaluated for abnormal hormone levels

  • Chromosome analysis: A blood sample is taken and analyzed in a lab to check the shape and number of chromosomes

Klinefelter Syndrome Treatment

Although there is no cure, early treatments can help minimize its effect. The earlier treatment is initiated, the more promising the outcome. Medical treatment may include:

  • Testosterone therapy

  • Surgical removal of male breast tissue (gynecomastia reduction surgery)

  • Speech and physical therapy

  • Additional education support

  • Fertility treatments

Contact Us

Interested in learning more about gynecomastia surgery and treatment options? Fill out Dr. Delgado’s contact form to begin exploring your options.

Resources and Support

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