GFR Measurement

A Glomerular Filtration Rate (GFR) measurement is carried out to measure how well your kidneys are working.

What is involved?

A small amount of radiation is injected into a vein, usually in your arm. The injection is no more painful than a blood test.

For the majority of patients, there will be a delay of three hours after the injection and then we will take a blood sample from another vein in your arm. For some patients, this blood sample will be taken at 6 hours after injection. The gap between injection and blood sample will be indicated on your letter. If you can, we would like you to leave the department between the injection and blood sample, but please attend for the blood sample at the time given to you by the technician or radiographer.

After the blood sample you will be free to go.

Do I need to do anything before and after the test?

• On the morning of the test, have a light breakfast as well as a light lunch e.g. a sandwich. It is recommended to avoid high protein meals on the day of the study until the blood sample has been taken.
• Do not consume any caffeine from 10pm the previous day as this can affect the result. Caffeine can be found in tea, coffee (including decaf varieties), hot chocolate, hard chocolate, green tea, coca cola, energy drinks and some cold/flu medicines.
• After the blood sample has been taken you can eat and drink as normal. You should drink more than usual for the rest of the day to help wash the injection out of your body. Whilst in the department and once the injection is complete, please use the designated radioactive toilet.

Is the radiation dangerous?

The substances we inject are non-toxic and will not make you feel sick or drowsy. The amount of radiation you will receive is small and your doctors consider that the benefit of you having this test significantly outweigh the small risk from this radiation.

However, for radiation safety reasons from other patients in the department, pregnant individuals and children should not be brought to the appointment unless they are the patient.

After your test you will still have some radioactivity in your body which will leave over time. You will emit a small amount of radiation which will be insignificant for most people around you. However, we ask that you try to avoid prolonged close contact with small children, babies and pregnant individuals for the rest of the day. The injection you will be given will not affect any pets you may have.

There is usually no problem to return to work following the scan. If your work involves radiation or close contact with children or pregnant individuals please ask Nuclear Medicine staff for advice.

What about pregnancy or breastfeeding?

Please tell us as soon as possible before the injection if you are pregnant or think that you may be pregnant. All patients between the ages of 10 - 55 years will be asked to complete a form on arrival.

There is no need to interrupt breastfeeding for this test.

What about my result?

As the blood samples will be analysed at a later time, we are unable to tell you the result of the test. The results will be sent to the doctor who requested the test.

Interpreter

If you need an interpreter for your appointment (including BSL) please contact Nuclear Medicine as soon as possible so this can be arranged for you. Family and friends are not legally allowed to interpret for you.

Consent

Please be aware that information from your examination may be used for teaching and evaluation purposes. Any information used will be anonymised. Should you not wish for details from your examination to be used in this way, please inform a member of the Nuclear Medicine staff when you attend.

Where can I get more information?

If you have any further questions after reading this information, please contact:

The Nuclear Medicine Department

Telephone number: 0300 019 2499

Email address: This email address is being protected from spambots. You need JavaScript enabled to view it.