Renal Scan (Kidney Scan)

What is a renal scan?

A renal scan is a nuclear medicine test to see how well your kidneys work. The kidney scan also shows how your kidneys look. The medical term for a kidney scan is renal scintigraphy.

Your healthcare provider injects small amounts of radioactive material (radioisotope or tracer) into your vein. You’ll pass through a scanner, which locates the radioactive material in your kidneys and sends images to a computer.

A kidney scan helps your healthcare provider detect kidney diseases and injuries at an early stage. Your healthcare provider also uses renal scans to check your progress after a kidney transplant.

When might I have a renal scan?

Your healthcare provider orders a renal scan when they suspect your kidneys aren’t working as they should. Healthcare providers may first see signs of reduced kidney function levels using blood and urine tests or an X-ray.

Your healthcare provider may also order a scan to check your kidneys if you:

• Are allergic to the dye used in X-rays, making a renal scan a safer option.
• Have had a kidney transplant.
• Have high blood pressure (hypertension).
• Have blocked urinary drainage from your kidney.

What conditions can a renal scan help diagnose?

Renal scintigraphy helps diagnose:

• High blood pressure in your renal arteries (renal hypertension).
• Hydronephrosis, swollen kidneys due to blocked urine flow from your kidneys to your bladder.
• Kidney cysts, tumors or pockets of pus (abscesses).
• Kidney disease, kidney failure or kidney injuries.
• Narrowed or blocked renal arteries (renal artery disease).
• Poor kidney function after surgery or a transplant.
• Reflux (backward flow) of urine from your bladder toward your kidneys (vesicoureteral reflux).

How does a renal scan work?

During a kidney test, a nuclear medicine technologist takes images of your kidneys. These images show blood flow into and out of your kidneys. They also show urine flow between your kidneys, ureters (which connect your kidneys and bladder) and bladder. The nuclear scan results help your healthcare provider see whether you have reduced kidney function or 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 your renal arteries (blood vessels in your kidneys) are narrowed, causing high blood pressure. Your healthcare provider looks at images of your kidneys before and after you take a blood pressure medication called an ACE inhibitor.
• Diuretic renal scintigraphy: This nuclear scan looks for kidney blockages or problems with urine flow. Your healthcare provider sees how urine moves through your kidneys by taking pictures before and after you take a diuretic (water pill).
• Renal cortical scintigraphy: This kidney scan checks the functioning of your renal cortical tissue (tissue in the outer part of your kidneys). A camera takes pictures about two hours after you receive an 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. A camera takes many pictures over a 20- to 30-minute period during the procedure.

How do I prepare for a kidney scan?

Before a renal scan, you’ll need to bring in a complete medication list, including vitamins and herbal supplements. Your healthcare provider may ask you to stop taking some of your medications a few days before your surgery. For instance, nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and aspirin, can affect kidney scan results.

Tell your healthcare provider if you’re:

• Allergic to certain medications or latex.
• Claustrophobic, as the camera could come uncomfortably close to you during the scan.
• Nursing, as the radioactive material could enter your breast milk.
• Pregnant or may be pregnant, as the scan could harm your baby.

Your healthcare provider may ask you to drink extra water before the test. Sometimes, you’ll need to empty your bladder before the exam starts.

Before the nuclear scan starts, remove all of your jewelry and metal objects or leave them at home. They can interfere with the exam.

What should I expect during the renal scan?

The length of your procedure varies by type of renal scan. In general, during the scan:

1. A nuclear medicine technologist inserts an IV line into a vein in your arm or hand. They place a radioactive material called a radioisotope or tracer into the IV. You might wait a short time or up to two hours (for renal cortical scintigraphy) while your kidneys process the tracer.
2. You lie or sit on the exam table. The tracer gives off energy called gamma rays. A gamma camera tracks the rays and creates pictures of your kidneys. The technologist views these images on a computer.
3. Depending on the purpose of the kidney scan, you may need to stay still or move into different positions. The kidney test takes from 30 minutes to two hours.

What should I expect after the kidney test?

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

The radioisotope leaves your body through your urine. You won’t feel any pain or discomfort from the tracer.

What are the risks of a renal scan?

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

Renal scan risks may include:

• Allergic reactions, though rare.
• Redness, swelling or pain at the site of the IV. Contact your healthcare provider if the discomfort doesn’t go away quickly.

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 findings and next steps in your treatment.

A note from Cleveland Clinic

Your healthcare provider uses a renal scan to diagnose specific kidney problems. This nuclear medicine test is an outpatient procedure that takes from 30 minutes to two hours. Your healthcare provider uses renal scan results to decide on the right treatments for any kidney function issues you may have. Renal scan risks are low and you can return immediately to your usual activities.