GFR Test

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Department of Nuclear Medicine

What is this information about?

This information is about your GFR Test.   

Why have I been given this information?

You have been given this information because your doctor has referred (sent) you for a GFR Test.  

Reading this information can help you to know what to expect from your scan. Following the advice will help to make sure that the test goes as well as it can.  

What is Nuclear Medicine?

Nuclear medicine: 

• is a safe and painless technique. 
• uses small amounts of radioactive materials as tracers to diagnose or treat disease. In diagnosing a condition, the radiation is detected by a special type of camera called a “Gamma camera”. 

What is a GFR Test?

GFR is a short term for Glomerular Filtration Rate. This is a measure of how your kidneys filter the body’s waste products from your blood. An estimate of your GFR is assessed on standard blood tests, however, to obtain greater accuracy of kidney function, this test uses a radioactive tracer to calculate how quickly it is removed from your blood.

What can I expect during my appointment?

•  We will give you an injection of a radioactive substance (‘radiotracer’) into a vein in your arm. The radioactivity does not last for long in your body.   
• After your injection you can leave the department if you wish. You must return for three blood samples over the course of the morning.
• The first sample is taken 2 hours after the radiotracer has been given.  We will put a cannula into a different vein, which will stay in your arm until all the samples have been taken.
• The second sample is taken an hour later.
• The third and last sample is taken an hour later.

Where should I go for my scan?

You will have your test in the Nuclear Medicine Department, St Richard’s Hospital.  

Use the main entrance to the Outpatients Department. This is in the South Wing of the hospital.  

Once you are inside the Outpatients Department, turn right and take the stairs or lift to the Department of Nuclear Medicine on the first floor. 

Wheelchairs are available just inside the entrance on the ground floor. 

If you are arriving by car, please use hospital entrance number 2.   

If you need to park, use the ‘pay on foot’ car park close to the entrance to the Outpatients department (South car park). Pay at the end of your parking session using the machines in the Outpatients department entrance. Disabled parking bays are available for the registered disabled near the main Outpatients’ entrance.  

How can I prepare for my GFR Test?

• Eating and drinking. Do not drink any caffeinated drinks in the morning before your test and until the test is completed. You can eat as usual.

• Medications. You do NOT need to stop any medication for a GFR Test. 

• Previous imaging scans. If you have had a CT or MRI scan that uses a contrast dye, within seven days of your GFR test, we may need to reschedule your appointment.

Might I have an allergic reaction to the radioactive injection?

Allergic reactions to the radiotracer are very rare but can happen.

Can I have a GFR Test if I am pregnant?

We will check your pregnancy status with you before the scan. If you are, or think you may be, pregnant you must tell us as soon as possible.  

Will I need to undress for my scan?

We recommend that you wear comfortable, loose clothing. You do not need to undress for your test.

What should I do if I cannot come to my appointment?

You must let us know as soon as possible if you are unable to attend. This is so that we can offer the appointment to someone else.

Important:

How long will the scan take?

GFR Tests can take up to 4 hours to collect all the samples. This includes the delays between your blood samples. You do not have to stay in the department between blood samples.

Who will be at my scan?

A radiographer or an assistant practitioner will be with you in the room during the scan.  

There are students training in the scanning department. A qualified radiographer will supervise them if they do your scan. Please tell us if you would prefer not to have a trainee at your scan.   

Are there any risks?

We are all exposed to natural background radiation every day. This comes from the ground, building materials around us, the food we eat and from the sun.   

This scan will give you a small extra radiation dose on top of this. The amount depends on the type of scan you are having. It ranges from a few days’ natural background radiation to a few years.  

After weighing up the risks and benefits your doctor has decided that having the scan is right for you. They believe that the potential benefits outweigh the risk.   

The radiation dose for the scan is listed in the table below, along with a comparison of radiation doses from other sources of radiation.   

The only effect known at these low doses is a very small increase in the chance that you might get cancer many years or even decades after the exposure.   

The additional cancer risks from these different sources of radiation are shown in the table below.   

These risk levels are a very small addition to the 1 in 2 chance we all have of getting cancer at some point during our lifetime. 

Can I drive home after my scan?

Yes.

When will I get my scan results?

The results will be sent to the doctor who asked for the examination and will usually be with them within 2 weeks. If you have an appointment sooner than this then please let us know so we can make sure the results are provided in time. 

Can I bring someone else with me to my appointment?

Yes. You can bring someone, such as a friend, relative or carer with you. They must be over the age of 16.

Important:

To protect other people from radiation, after you have had your radiotracer injection, plan to keep a distance of at least 1 metre from them until the end of the day. For further advice please contact the Nuclear Medicine Department.  

How is my medical data protected?

Everyone working within the NHS has a legal duty to keep patient information about you confidential & secure. If you have any concerns around the use of your medical and diagnostic imaging information, copies of the “Care Record Guarantee” and “Your Medical Data” leaflets can be downloaded from: www.uhsussex.nhs.uk 

You can get a printed copy of these leaflets from the PALS (Patient Advice and Liaison) office at Worthing or St Richard’s, Chichester, Hospitals. 

Who can I contact if I need further information or support after I have read this information?

I need help with transport to my appointment for medical or financial reasons. What help is available?

To find out what help with transport you may be able to get please visit the UHSx Patient Transport web page www.uhsussex.nhs.uk/patients-and-visitors/patient-transport. 

• To enquire about booking the hospital transport service phone: 0300 777 4444 

• To check whether you can get help with the cost of transport, phone the St Richards Hospital switchboard 01243 788122 and ask for the Cashiers Office. 

Important: