Children and Young People’s Endocrine Team
Your child has been asked to come for an LHRH (GnRH) test
This is either because he or she has been referred to the consultant endocrinologist with possible signs of early pubertal development or because we would like to evaluate his or her pubertal status
What happens during puberty?
During puberty, special messenger hormones are released by a gland in the brain called the pituitary gland. These messenger hormones are called FSH (Follicle Stimulating Hormone) and LH (Leutinising Hormone)
They act on the ovaries and stimulate the production of the hormones oestrogen and progesterone which are responsible for the development of female sexual characteristics – breast development, maturation of the womb and the start of menstrual periods
They act on the testes to stimulate the production of testosterone which is responsible for the development of male sexual characteristics – growth and maturation of the testes and penis and the production of sperm.
The age of onset of puberty is varied but is usually between the ages of 9 and 14 years. The duration of puberty can be anything from 18 months to 5 years but it is usually progressive and it follows a set pattern.
The first sign
Breast development (breast buds followed by progressive enlargement) followed by pubic hair and then the onset of periods and change in body shape.
The first signs are a little less noticeable and start with the enlargement of the testes within the scrotal sac; this is followed by progressive enlargement of the testes and penis, the development of pubic hair, facial and body hair, deepening of the voice and change in body shape.
During puberty there is also a growth spurt – usually in the early stages in girls and around halfway through in boys, which is why boys end up significantly taller.
Once puberty is nearing completion, the growth rate will slow down and the growth plates (the growing ends of the bones) will fuse and growth will eventually stop.
When is puberty too early?
When physical changes begin earlier than the age of 8 years in a girl or 9 years in a boy, an assessment needs to be made by a specialist to determine the cause of the early development.
- Pubertal development usually follows a familial pattern, so if one of both parents went into puberty earlier or later than usual then the child could also follow this pattern
- In some children one or more signs of puberty are “switched on” a little earlier than usual
- The consultant will have taken a detailed history when you were seen in the endocrine clinic, together with a physical examination of your child
- In order to determine if your child has truly gone into early puberty, the consultant will have asked for some further investigations
- They may have been referred for an ultrasound scan of their abdomen – to look at the size and maturation of the womb and ovaries in girls or in boys to determine the position of the testes, if an examination has found that they are not situated within the scrotum.
- They may have been referred for a scan of their brain to look at the pituitary gland – more so in boys because early pubertal signs in a boy could arise from problems within this gland
- They will have been referred to the endocrine nurse to perform an LHRH test and possibly some other blood tests in order to assess the production of puberty hormones.
You have been asked to come to Children’s Outpatients. This is situated in the South Entrance to the hospital – through the large revolving doors in front of the blue globe, second on the left just past the lifts.
Please note that there is a parking charge and parking can occasionally be a problem, so please allow sufficient time before your appointment to find a parking space.
The LHRH Test
It will normally take approximately and hour to complete and you should expect to be in the Department for around 60 to 90 minutes in total.
There is no special preparation needed for this test – your child can eat and drink normally before and during the test.
We will weigh your child when they arrive in order to work out the dose of LHRH they will need to adequately stimulate the production of the hormones LH or FSH oestrogen or testosterone
A cannula – a small plastic tube (a bit like a tiny drinking straw) will be inserted into one of the veins either on the back of the hand or inside of the elbow.
The cannula is inserted with the assistance of a needle which passes through the tube, piercing the skin and the wall of the vein. The needle is then removed and the plastic tube is left in place inside the vein. It is secured with sticky tape and a bandage and flushed with some salty water to stop the blood from clotting around it and blocking it.
We normally use special local anaesthetic spray to freeze the area which works straight away or alternatively we can use local anaesthetic cream to numb the area. This takes around 45 minutes to an hour to work.
If your child is especially anxious we can discuss other methods of pain relief. We have a variety of distraction techniques that we can use; it may also be helpful to bring their favourite electronic game, toy or book to help distract them.
Once the cannula is in place, a sample of blood will be taken from it to measure the amount of LH or FSH and oestrogen or testosterone your child has in their blood stream. This is called the baseline level (0 minutes)
A dose of LHRH (LH or FSH releasing hormone) called Gonadorelin will be prescribed and given intravenously (IV) through the cannula.
LHRH is a special messenger hormone which stimulates the pituitary gland to make some of the puberty hormones LH and FSH. There should not be any side effects from this, but your child will be observed closely for the duration of the test and any irregularities will be dealt with accordingly.
Further blood samples are taken from the cannula 30 minutes after the LHRH is given and again 60 minutes afterwards; this will measure the amount of puberty hormones your child has produced in response to the stimulation from the LHRH
After the final blood sample the test is complete, the cannula will be removed and you will be allowed home.
Once the Doctor has the results, they will determine if full puberty has started (this is known as precocious puberty) or if just one or two areas have been switched on a little earlier than expected
Once we have the results, you will be given the opportunity to discuss them at your next appointment, where the next course of action will be decided. If you wish to know the results before you see the consultant, please contact their secretary but please be assured that if they are abnormal we would contact you.
If you have any further questions regarding the test, please do not hesitate to contact us:
Childrens Endocrine nurse – Julie Stonehouse
Telephone: 01642 854660
Dr Burns, Dr Balasubrahmanyam, Dr Raman’s – Secretaries
Telephone: 01642 282723 or 01642 837187
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