Renal Scan (Kidney Scan)

What is a renal scan?

A renal (kidney) scan is a nuclear medicine imaging test to see how well your kidneys work. It also shows how your kidneys work.

A healthcare provider injects small amounts of radioactive material (radioisotope or radiotracer) into a vein, usually in your arm or hand. The radioactive material travels through your veins into your kidneys. Then, you’ll pass through a scanner, which locates the radioactive material in your kidneys and sends images to a computer.

A renal scan helps providers detect kidney diseases and injuries at an early stage. They also use renal scans to check on your kidney after a kidney transplant.

Other names for a kidney scan include:

• Renal scintigraphy (REEN-uhl sin-TIG-ruh-fee)
• Nuclear medicine renal scan
• Nuclear medicine kidney scan
• Renogram

What does a renal scan show?

A renal scan shows how your kidneys work. A renal scan also shows your kidneys’:

• Shape
• Size
• Position in your body

Why would you be sent for a kidney scan?

Healthcare providers order renal scans when they suspect your kidneys aren’t working as well as they should. They may first see signs of reduced kidney function levels using other tests, including:

• Blood tests
• Pee tests (urinalysis)
• X-rays

A provider may also order a renal scan to check your kidneys if you:

• Are allergic to the dye in X-rays, making a renal scan a safer option
• Have a transplanted kidney
• Have high blood pressure (hypertension)
• Have kidney blockage that makes peeing difficult or impossible

What conditions can a renal scan help diagnose?

A renal scan helps diagnose:

• High blood pressure in your renal arteries (renal hypertension)
• Swollen kidneys due to blockage (hydronephrosis)
• Kidney cysts, kidney tumors or pockets of pus (abscesses)
• Narrowed or blocked renal arteries (renal artery stenosis)
• Poor kidney function after surgery or transplant
• Pee flowing back from your urinary bladder toward your kidneys (vesicoureteral reflux)

How does a renal scan work?

During a renal scan, a healthcare provider with specialized training in using radioactive drugs and imaging machines (nuclear medicine technologist) takes images of your kidneys. The images show how blood flows into and out of your kidneys. They also show how pee flows between other organs in your urinary system, including your:

• Kidneys
• Ureters
• Bladder

The nuclear scan results help your provider see whether you have reduced kidney function or a blockage.

What are the types of renal scans?

Nuclear medicine technologists use four kinds of renal scans:

• ACE inhibitor renal scintigraphy. This kidney test looks at whether the blood vessels in your arteries are narrow, causing high blood pressure. A provider looks at images of your kidneys before and after you take a blood pressure medication (ACE inhibitor).
• Diuretic renal scintigraphy. This nuclear scan looks for kidney blockages or problems with your pee flow. A provider sees how pee moves through your kidneys by taking images before and after you take a water pill (diuretic).
• Renal cortical scintigraphy. This kidney scan checks how well the tissue in the outer part of your kidneys (renal cortical tissue) works. A camera takes pictures about two hours after you receive an intravenous line (IV) with radioactive material.
• Renal perfusion. This nuclear medicine test looks at blood flow to your kidneys. The renal scan measures the width of your renal arteries and how well your kidneys work. Over 20 to 30 minutes, a camera takes many pictures.

How do I prepare for a renal scan?

Before a renal scan, you’ll need to make a complete list of medications that you take. This list should include vitamins and herbal supplements. You may need to stop taking some medications a few days before your renal scan. For instance, nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen (Advil®, Motrin®) and aspirin (Bayer®, St Joseph®), can affect your kidney scan results.

It’s also important to tell healthcare providers if you:

• Have any allergies, including certain drugs or latex
• Have claustrophobia, as the camera may come close to you during the scan
• Are afraid of needles (trypanophobia), as they can recommend coping strategies
• Are breastfeeding, as radioactive material may enter your milk
• Are or may be pregnant, as the scan could harm the fetus

Providers may ask you to drink extra water before the renal scan. You may also need to empty your bladder (pee) before the scan starts.

It’s also a good idea to wear comfortable clothes and leave any metal accessories at home, including eyeglasses and jewelry. They can interfere with the scan.

What should I expect during the renal scan?

In general, during a kidney scan, you can expect the following:

1. A nuclear medicine technologist inserts an IV line into a vein, usually in your arm or hand. Then, they insert a radioisotope or radiotracer into the IV.
2. You lie or sit on an exam table. The radioactive material gives off energy (gamma rays). A gamma camera tracks the rays and creates images of your kidneys. The technologist views these images on a computer.
3. Depending on why you need the kidney scan, you may need to stay still or move into different positions.

How long does a renal scan take?

The length of the procedure varies by the type of renal scan. It may take between 30 minutes and two hours to complete. A healthcare provider will give you an expected timeframe.

What should I expect after a renal scan?

After the nuclear medicine technologist removes your IV, you may go home. You can return to your everyday activities immediately.

How does a radiotracer leave my body?

The radiotracer or radioisotope leaves your body when you pee. It won’t cause any discomfort or pain.

What are the risks of a renal scan?

The risks of a kidney scan are very low. The scan uses less radiation than an X-ray.

Renal scan risks may include:

• Allergic reactions (rare)
• Discoloration (red, purple, brown, or black), swelling or pain at the IV site (contact a healthcare provider if the discomfort doesn’t go away after a few days)

It’s also a good idea to avoid close contact with children and pregnant women for a few hours after the procedure.

When should I know the results of my kidney scan?

A nuclear medicine technologist or radiologist reviews the results of your renal scan. Then, they send a report to your healthcare provider. Your healthcare provider will contact you to discuss the findings and any next steps in your treatment.

If the results are abnormal, what are the next steps?

If your results are abnormal, your healthcare provider may recommend more testing to make an official diagnosis. These tests may include:

• Additional imaging tests, including an ultrasound, MRI and/or CT scan
• Additional kidney function tests
• Kidney biopsy

When should I call my doctor?

Call a healthcare provider if you have any questions about your renal scan, including:

• How to prepare for the scan, including how to make the test easier for you
• When to expect your results
• What to do if you have abnormal results
• What your next steps are

You should also contact a provider if you:

• Have signs of an infection, including a fever, discoloration around your IV site, swelling or a headache
• Think you’re having an allergic reaction