hCG test

Hormones are chemical messengers that switch on and off processes within the body. Human Chorionic Gonadatrophin (hCG) is a hormone that mimics the action of luteinising hormone which is normally produced by the pituitary gland. The hCG test allows doctors to measure the amount of sex hormones being produced in the body naturally.

In boys, luteinising hormone and therefore hCG tells the testes to produce the male sex hormone (testosterone). In girls, the hCG tells the ovaries to produce progesterone but this only happens later in development. As a result the hCG test is more useful in boys than girls.

What is a hCG test and why does my child need one?

The hCG test allows doctors to measure the amount of sex hormones being produced in the body naturally. This can be useful in investigating hormonal problems, such as delayed or early puberty. It can also be used to check whether the testicles or ovaries are able to produce hormones in conditions like undescended testicles or ambiguous genitalia. This type of hCG test is carried out over four days but quite important information can be obtained by extending the test over three weeks.

What happens before the test?

You will usually need to come to the hospital on a Monday so that the doctors can explain about the test in more detail, and discuss any worries you may have. If your child has any medical problems, particularly allergies please tell the doctors about these. Please also bring in any medications your child is currently taking. You will then need to return to the hospital on the Thursday of that week.

What does the test involve?

The test takes between four days and three weeks depending upon the question that the doctors wish to answer. On the first day, Monday, the nurses will take a sample of blood to send to the laboratory. They will measure the level of sex hormones in the body before the test starts. The nurse will then give your child an injection of hCG into the leg muscle.

On the second and third days, your child will need a further injection of hCG, again into their leg. These injections can be given at your GP surgery if this is more convenient. We will give you the injections and forms to take to your GP.

On the fourth day,Thursday, the nurses will take another sample of blood to measure the level of sex hormones in the body once the test is completed.

If your child is having the three-week test, he or she will have another injection of hCG after this blood test. Your child will need to be examined closely on the ward and the doctors may ask for clinical photographs to be taken for his or her records. We will ask for your permission to have these photographs taken. Your child will then have a total of four more injections of hCG over the next two weeks. After the injections, he or she will be examined again on the ward and have another blood test.

Are there any risks?

Blood samples can hurt, but we will apply local anaesthetic cream to your child’s hand where possible, so the pain is minimised. The hCG injections into the leg muscle may hurt a bit, but as the injection is so quick the pain goes away quickly too. If your child is having hCG injections over three weeks, the appearance of his or her genitalia may begin to change. This is quite normal and shows that the injections are working.

How long will it take to get the results?

It can take around six weeks to get the results of this test, as there are so many substances in the blood to check. If possible, your child’s test results will be given to you at your next outpatient appointment at the hospital. However, if there is a need to start on new treatment before the appointment, the hospital will contact your GP. 

Compiled by: 
Kingfisher Ward in collaboration with the Child and Family Information Group
Last review date: 
October 2013


Please note this is a generic GOSH information sheet. If you have specific questions about how this relates to your child, please ask your doctor. Please note this information may not necessarily reflect treatment at other hospitals.