Diagnostic Tests for Kallmann's Syndrome and Hypogonadotrophic Hypogonadism

Function tests:

In order for a doctor to determine if the pituitary and hypothalamus are functioning correctly specific function tests may be ordered.

hCG stimulation test.

hCG is human chorionic gonadotrophin. It has the same biological function as the pituitary hormone, luteinising hormone (LH). It should stimulate the testes to produce testosterone.

A baseline testosterone level is taken. A set dose of hCG is given and then a further measurement of testosterone is taken after 72 hours. A positive result will indicate how well the testes respond to pituitary stimulation. It also could indicate if the testes are present & active if they have not descended into the scrotum. In some cases of cryptorchidism, where the testes are still hidden, imaging tests such as a MRI scan may be required to locate them.

GnRH stimulation test.

GnRH is the hormone released by the hypothalamus to stimulate the pituitary to produce its own hormones. It is sometimes called LHRH - luteinising hormone releasing hormone

It can be used to distinguish between a delay in puberty rather than a case of HH.

Baselines levels of LH and FSH are taken. A set dose of GnRH is given. The levels of the LH and FSH are then retested after 45 minutes.

In a case of delayed puberty the levels of LH and FSH are raised after the first attempt.

In HH the test has to be repeated over several days in order to get the increase in LH and FSH because the pituitary needs to be 'primed' to be able to respond to the GnRH. In most cases of delayed puberty the pituitary has already been primed and should respond more quickly.