Kallmann Syndrome

Kallmann syndrome is a condition that’s characterized by absent or delayed puberty and a lack or loss of sense of smell. Kallmann syndrome may be accompanied by other symptoms, including hearing loss and cleft palate. The condition is typically treated with hormone replacement therapy.


What is Kallmann syndrome?

Kallmann syndrome (KS) is a type of hypogonadotropic hypogonadism (HH) — a condition that occurs due to a lack of sex hormone development. People with Kallmann syndrome experience absent or delayed puberty and a lack or loss of sense of smell (anosmia). In some cases, Kallmann syndrome can also affect your mouth, ears, eyes, kidneys and heart. When a person has the characteristics of Kallmann syndrome without anosmia, it’s called normosmic idiopathic hypogonadotropic hypogonadism (nIHH).


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Who does Kallmann syndrome affect?

Kallmann syndrome is a congenital condition, which means people are born with it. Statistically, the condition occurs in 1 out of every 30,000 males and 1 out of every 120,000 females.

How does Kallmann syndrome affect my body?

During typical development, your hypothalamus releases bursts of hormones during puberty called gonadotropin releasing hormone GnRH. This triggers your pituitary gland to produce hormones — and as a result, your gonads (testicles or ovaries) produce sperm and egg cells, respectively. Kallmann syndrome is due to genetic defects leading to the underdevelopment of GnRH production. As a result, puberty is delayed or absent.

Why does Kallmann syndrome have anosmia?

Research indicates that gene mutations associated with Kallmann syndrome affect olfactory (sense of smell) nerve cells in your brain. As a result, your sense of smell is impaired.


Symptoms and Causes

What are the symptoms of Kallmann syndrome?

There are several symptoms associated with Kallmann syndrome, and they can vary from person to person. Kallmann syndrome symptoms in children may include:

  • A lack of breast development and menstrual periods in females at puberty.
  • No development of sex characteristics in males at puberty, such as enlarged penis and testes, facial hair and deepening of their voice.
  • Short stature (in some cases).
  • Anosmia (in some cases).

Kallmann syndrome symptoms in adults may include:

  • Decreased energy or fatigue.
  • Weight gain.
  • Mood changes.
  • Decrease or loss of menstrual periods in females.
  • Low sex drive in males.
  • Infertility.

Some people with Kallmann syndrome also have other features unrelated to reproductive health. These may include:

  • Renal agenesis, a condition in which one kidney doesn’t develop.
  • Cleft lip and palate.
  • Dental abnormalities.
  • Poor balance.
  • Scoliosis, a condition characterized by curvature of the spine.
  • Eye movement abnormalities.

Is hypogonadotropic hypogonadism hereditary?

Both Kallmann syndrome and nIHH are genetic conditions caused by gene mutations. There are several different gene mutations, and most (but not all) have been linked to an inheritance pattern. For example, some forms of the condition are inherited from either the mother or the father, while others are inherited by both parents.


Diagnosis and Tests

How is Kallmann syndrome diagnosed?

Parents usually notice a lack of sexual maturation during puberty which prompts them to make an appointment with their child’s healthcare provider. They’ll examine your child and ask questions about their symptoms. If Kallmann syndrome is suspected, their provider may order more tests, including:

  • A hormone evaluation.
  • Olfactory function testing to test your child’s sense of smell.
  • Imaging tests, such as magnetic resonance imaging (MRI) to assess the olfactory bulbs in their brain.
  • Genetic testing.

Management and Treatment

How is Kallmann syndrome treated?

Kallmann syndrome is usually treated with hormone replacement therapy. Specific methods depend on the source of the issue, but options may include:

  • Testosterone injections, skin patches or gels for males.
  • Estrogen and progesterone pills or skin patches for females.
  • GnRH injections, which may be used to induce ovulation in females who don’t have regular ovulation or menstrual periods.
  • HCG injections, which can be used to increase sperm count in males and increase fertility in females.

Outlook / Prognosis

What happens if Kallmann syndrome is left untreated?

Kallmann syndrome is not a life-threatening disease. However, if left untreated, the condition leads to infertility in both males and females.

Can Kallmann syndrome be cured?

There's currently no known cure for Kallmann syndrome. However, continued research is being performed in this area.

Is Kallmann syndrome reversible?

In some cases, males with Kallmann syndrome experience a reversal of the condition. This is marked by fertility in the absence of treatment or an improvement in testosterone secretion even after discontinuing testosterone replacement. When this happens, it’s called reversible KS — a condition that has, to date, only been reported in males.

Living With

When should I see my healthcare provider?

If your child hasn’t started showing signs of puberty around the same time as their peers, then it’s a good idea to schedule a visit with their healthcare provider. They can run the appropriate tests and talk with you about treatment options.

If you’re an adult with Kallmann syndrome and you want to explore fertility options, schedule a visit with your healthcare provider. They can prescribe medications to help you or your partner conceive.

A note from Cleveland Clinic

Kallmann syndrome can present some challenges during puberty. But when diagnosed and treated early, many people with the condition enjoy improved reproductive health and a better quality of life. If you or your child has been diagnosed with Kallmann syndrome, consider joining a support group. Talking with others who are going through the same things can be beneficial for your mental and emotional wellbeing.

Medically Reviewed

Last reviewed on 05/25/2022.

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