A small amount of the tracer is injected into the blood and the test finds out how quickly it is removed from the body.
Why is this test needed?
Your doctor will explain why your child needs a more accurate test to measure the kidney function.
Some common reasons are:
- to help your doctor decide how often your child needs other tests
- to help your doctor give you more accurate information about the outlook for your child
- to allow your doctor to adjust the amount (dose) of medicines that your child may need. If their kidneys are not working normally, they may need a smaller dose for example
- if your child has other problems that make the estimating method less accurate, for example abnormal muscles
Preparing for the test
You and your child do not need any special preparation for this test. Your child can eat and drink as usual, unless your doctor tells you otherwise.
You can be with your child during the whole test.
What happens?
- A small amount of the liquid radioactive tracer is injected into a vein in your child's arm.
- Your child will then have several small samples of their blood taken – this is often at two, three and four hours after the injection.
A play specialist may be able to meet with your child. They will use toys to help your child prepare for the test.
Are there any risks?
If your child’s doctor recommends this test, they will have considered that the benefits outweigh any risks. A small amount of the radioactive substance is used and it will not be in your child’s body for long. The radiation exposure from this test is similar to the natural background radiation that your child receives in one week.
Are there any other options?
The alternative to this test is to continue use the estimating method – the single blood test to measure creatinine.
After the test
There may be a small amount of radioactive substance in your child’s urine for 24 hours after the test.
Your child should sit on the toilet to urinate (wee) for the day after the test.
If your child uses nappies, put used nappies in a separate bag for 24 hours, then throw them away in your normal rubbish.
If your child accidentally wets their clothes or bedding, put these in a separate bag for 24 hours and then wash them as normal.
Finding out results
You will not get the results on the day of the test. They will be given to your doctor who will explain to you what the results mean.