CHH and Kallmann syndrome

Congenital hypogonadotropic hypogonadism (CHH) is characterised by a deficiency of the gonadotropin releasing hormone (GnRH) in the brain. It is a genetic disorder which prevents spontaneaous puberty. Some men also have a problem with their sense of smell (Kallmann syndrome).




Congenital hypogonadotropic hypogonadism (CHH) is usually diagnosed when a child does not go into puberty.

Typical characteristics of congenital hypogonadotropic hypogonadism (CHH) are:

  • In boys: small testicles, a small penis, undescended testicles, reduced beard growth and body hair, less muscle mass and a reduced libido
  • In girls: no or little breast development

Additional symptom in Kallmann syndrome

A typicial additional sympom in case of the Kallmann syndrome:

  • An impaired sense of smell


The cause of a congenital hypogonadotropic hypogonadism is an absent or distorted production of the gonadotropin releasing hormone (GnRH) in the brain. This will stop the brain from sending signals to the reproductive organs, stopping the production of sex hormones. This will halt puberty and cause infertility.

In addition to the impaired production of sex hormones, Kallmann syndrome also presents patients with a problem with the sense of smell (absent or strongly reduced), caused by the fact that the part of the brain that is used to smell has not been formed.


The treatment consists of the administration of sex hormones.

  • In men: testosterone
  • In women: Progesterone and oestrogen

Fertility treatment may be required in case of a pregnancy wish.

Follow-up at the endocrinologist

The endocrinologist is best placed to coordinate the medical problems related to congenital hypogonadotropic hypogonadism and Kallmann syndrome, and if necessary to refer to other specialists concerned (fertility specialist ... ).

Examinations and diagnosis

In case of (suspicion of) this disorder, we will run one or several tests.

Last edit: 27 October 2020