What is a GFR test?

GFR stands for Glomerular Filtration Rate. This is a measure of how well your kidneys are working to filter your blood. A nuclear medicine GFR test uses a small amount of radioactivity to measure the overall function of the kidneys. It will check how quickly a liquid (radioactive tracer) disappears from your blood. A GFR test gives a correct measure of how well your kidneys are working. It cannot tell how well each kidney works on its own.

Do I need to have this test?

A doctor will have checked to make sure this is the correct test for you.

If you have any concerns or would like further information contact the department where you are having this test. If you do not understand why you need to have this test please speak to the doctor who referred you.

Is it safe?

The materials (radionuclides) used in nuclear medicine to find the problem are generally safe. They have a short half-life and leave the body naturally, for example through urine. The small radiation risk is outweighed by the information that will be found by having the test.

How do I prepare for my test?

We will have discussed the preparation with you by telephone. If this has not been done, please ring us. Usually you will be asked to:

  • Have a light, low protein breakfast on the day of the test
  • Avoid caffeine
  • Drink water normally
  • Bring a list of your current medications to your appointment

It is IMPORTANT to let us know if you have any scans (CT, MRI or PET) booked within 48 hours before your GFR test appointment or you have a current urinary tract infection (UTI).

What if I am pregnant or breast-feeding?

If you know that you are pregnant, or there is any chance that you may be pregnant, then please contact the department on the following numbers. Your test will need to be postponed. Also let us know if you are breast-feeding. We have special instructions for you:

Cumberland Infirmary, Carlisle: 01228 814701
West Cumberland Hospital, Whitehaven: 01946 523456

What will happen?

Your Injection

A small amount of liquid (radioactive tracer) will be injected into a vein in your arm or hand using a small needle. We will take three blood samples at 2, 3, and 4 hours after the injection. Sometimes we only take one blood sample at 4 hours after the injection. This will still give accurate results. During the time between injection and blood samples you can leave the department. We will tell you when you need to come back.

Taking Blood Sample/s

We will put a needle (cannula) in your hand or arm and take bloods from there. The blood samples tell us how much of the radioactive tracer has been processed by the kidneys.

After Your Test 

When your test is finished you can continue all your normal activities unless you have been advised not to.

A tiny amount of radioactivity will still be left in your body. This will not be a risk to other people. The radioactivity will break down on its own. For the rest of the day we suggest that you drink plenty of liquids. This will help clear the radioactivity quicker.

Travelling Abroad 

It is safe for you to travel abroad after your test. Many airports and seaports have very sensitive radiation detectors. It is possible that the very small amount of radioactivity left in your body could set off an alarm when you go through security. If you are going abroad within 1 week after your test take something with you to explain that you have recently had a nuclear medicine test. This could be your appointment letter or some other official confirmation from the department where you had your test.

Your Results 

A nuclear medicine physicist will report your test results. The report will be sent to the doctor who asked for the test rather than to your GP. Unless your GP asked for the test. This is because the doctor who asked for the test will have all the results from other tests. They will be able to tell you how the result of your test affects your care plan.

Confidentiality

‘The Trust’s vision is to keep your information safe in our hands.’ We promise to use your information fairly and legally, and in-line with local and national policies. You have a right to understand how your information is used and you can request a copy of the information we hold about you at any time.

For further information on confidentiality contact the Information Governance Team:

Information.Governance@ncic.nhs.uk | 01228 603961

Feedback

We appreciate and encourage feedback, which helps us to improve our services. If you have any comments, compliments or concerns to make about your care, please contact the Patient, Advice & Liaison Service:

pals@ncic.nhs.uk | 01228 814008 or 01946 523818

If you would like to raise a complaint regarding your care, please contact the Complaints Department:

complaints@ncic.nhs.uk | 01228 936302