Q3a. What causes Kallmann syndrome ?

The underlying cause of Kallmann syndrome is the breakdown of the communication between the hypothalamus and the pituitary glands.

If the hypothalamus is unable to release the correct hormone, known as GnRH, gonadotropin releasing hormone, the pituitary gland is not able to release the hormones, LH and FSH, which means the ovaries and testes remain in a dormant state and can not function correctly.

In most forms of Kallmann syndrome and CHH both the testes and the ovaries are formed correctly but remain in a dormant, inactive state due to the lack of FSH and LH normally produced by the pituitary gland.

Kallmann syndrome and CHH are hormonal conditions and should be treated by an endocrinologist, ideally a reproductive endocrinologist who specialises in problems with the hypothalamus and pituitary glands.

There are two major reasons why the hypothalamus is unable to release GnRH correctly:

1. Lack of GnRH releasing nerve cells (neurones) within the hypothalamus
2. Breakdown in the precise timed release of GnRH from the hypothalamus