Here are some basic facts on Klinefelter Syndrome, also known as XXY Syndrome. These Klinefelter facts will help you understand the disease and understand the treatment options available.


What are the variants found in Klinefelter Syndrome?

80% – 90% of boys affected by Klinefelter Syndrome

10% of boys affected by Klinefelter Syndrome

Very rare cases of Klinefelter Syndrome


Klinefelter Statistics

Most males who are infertile and have small testicles (grape size) due to a chromosomal disorder have Klinefelter syndrome with a 47,XXY karyotype (extra X and Y chromosomes) or a variant.

In Australia, 1 in 650 males is born with Klinefelter syndrome. In the U.S.A., 1 in 500-1,000 males has an extra sex chromosome.

Klinefelter syndrome is significantly under-diagnosed in the general population.

If your healthcare practitioner is unfamiliar with the finer details of Klinefelter syndrome, you can download this free booklet and give it to them.


Klinefelter treatment options

Boys with Klinefelter syndrome do not need a special diet, or to restrict their activities. Hospital care is not required. Treatment is on an out-patient basis.

Testosterone is the treatment of choice for Klinefelter syndrome.

Testosterone can reduce the gonadotropin level to high normal. Gradually, testosterone will virilize the boy, giving him male secondary sex characteristics, like a beard, body hair, and a male-pattern fat distribution.

When your son is 11 or 12 years old, the doctor will commence testosterone supplementation. Testosterone treatment options include injections, gels and scrotal cream.

testosterone injections

Common testosterone injections options include:

Testosterone enanthate (Trade Name: Delatestryl® Primoteston® Depot)
Testosterone esters (Trade Name: Sustanon®)
Testosterone cyprionate (Trade Name: Depo-Testosterone)
Testosterone undeconate -slow release (Trade Name: Reandron®, Nebido® Not available in the USA)

Testosterone injection treatment (using short-acting injections) usually begins with a 50mg dose on  a monthly basis.



AndroGel vs AndroForte

Common topical testosterone options include:

Transdermal gels (1% testosterone gel AndroGel®, Testogel® or Testim®) can be applied daily to the arms, chest, back and shoulders.

Testosterone cream (AndroForte® 2 and AndroForte® 5) can be applied either transdermally, but preferably scrotally once daily.


The doctor will closely monitor your son’s growth and the development of male secondary sex characteristics. Your son will need to have blood drawn to check the gonadotropin hormone levels.

In years past, adult males with Klinefelter syndrome visited the doctor every two or three weeks to receive an intramuscular injection of 200 – 250 milligrams of testosterone enanthate, esters or cyprionate or at 6-monthly intervals for 600 -1000 milligrams testosterone implants.

More recently testosterone gels (AndroGel®, Testogel® and Testim®) have allowed patients to self administer their testosterone requirements. Testosterone gels are applied to the body – abdomen, chest, shoulders and arms.

AndroForte® (2% and 5% strength) scrotal testosterone creams are the most recent and user friendly advance in testosterone administration. Scrotal skin is significantly more receptive to testosterone absorption due to its high blood flow, thin skin and low fat content. Testosterone cream applied to the scrotum achieves significantly higher testosterone blood levels than the equivalent amount of testosterone applied to other areas of the body. This represents significant cost savings to patients. Because testosterone gels are alcohol based they cannot be applied scrotally due to the sensitivity of scrotal skin.

Unlike intramuscular injections and implants, the cream is painless. The daily dose you receive with cream is even. Injections produce uneven testosterone blood levels because they wear off and have to be replenished every 7 – 22 days.


Specialists that you will need to book appointments with: 

You and your child can also benefit from consulting with these specialists:

Geneticist: A geneticist can diagnose Klinefelter syndrome before your son is born through a fetal cytogenetic analysis. A genetic counselor may help you explain Klinefelter syndrome thoroughly to your affected son.

Endocrinologist: A hormone specialist can regularly monitor the effectiveness of the testosterone replacement therapy. The endocrinologist will order blood tests for testosterone, FSH, LH, and estradiol. The endocrinologist may order an echocardiogram for mitral valve prolapse, x-rays, and a bone density test for osteoporosis.

Physiotherapist (PT): Your affected son may have weak, flaccid muscles and slow reflexes (hypotonia). Klinefelter syndrome could make him clumsy, unbalanced, uncoordinated, and with poor posture. Ask your family physician to refer you to a physiotherapist familiar with
Klinefelter syndrome.

Speech therapist: Your son may require help to understand complex language before he starts school. Ask your family physician for a referral to a speech therapist.

Occupational Therapist (OT): Your son may have motor dyspraxia, a nervous system disorder where he has difficulty planning and executing complex movements and tasks. Obsolete terms for dyspraxia are clumsy child syndrome, congenital maladroitness, and sensory integration disorder. Dyspraxia often co-occurs with learning disabilities, dyslexia, and attention deficit disorder. An Occupational Therapist (OT) can train your son to appear less clumsy. The OT can fit your child with small, inconspicuous, and inexpensive assistive devices, like pen grips.

Psychologist: Enlarged breasts place psychological stress on affected men, so seek help from a psychologist familiar with Klinefelter syndrome. Visit The Australian Psychological Society at www.psychology. to find a local psychologist suitable for your needs. The American Psychological Association at offers a similar service.

Special Ed: Get a thorough psychoeducational examination through your son’s school. The written evaluation you will receive from the Special Education Department lists your son’s strengths and weaknesses, and recommends an appropriate classroom placement. A psychoeducational exam will list additional resources available in your area, so you can tailor your son’s education.

Surgeon: You may want to consult a surgeon about mastectomy (breast removal) or breast reduction. Around 10% of XXY males have breast enlargement great enough to require surgery. Gynecomastia increases the chance of breast cancer.

Fertility Experts: Not all men with Klinefelter syndrome are infertile. Some have oligospermia (low sperm production). If you wish to father a child and have a low sperm count, a fertility expert may be able to extract sperm directly from your testicles during a biopsy, choose one that is viable, and inject it into a woman’s egg. This process is called ICSI (intracytoplasmic sperm injection). The resulting child will not have a risk of developing Klinefelter syndrome above that of the general population. If the specialist finds more than one viable sperm, you may choose to have them frozen for future pregnancies. To date, more than 60 children have been born to Klinefelter men around the world through ICSI.


Understand more on Klinefelter:

What is Klinefelter Syndrome?

Diagnosing Klinefelter Syndrome

Why we need testosterone

The information in this article has been taken with permission from the official Lawley booklet on Understanding Kinefelter Syndrome.