Your kidneys are on either side of your spine, near your lower back. They filter blood and help balance water, salt and mineral levels. They also produce hormones that help regulate your blood pressure and blood supply. When your kidneys aren't working it can affect your entire body. However, the early signs of kidney issues often present few or no noticeable symptoms. A kidney scan can give your doctor critical information about the organ's function and appearance.
Why you might need a kidney scan
A kidney scan is a nuclear imaging test that evaluates how your kidneys are functioning and examines their structure. The images gathered from the scan can help your doctor:
-
Check the blood flow through the kidneys
-
See how a transplanted kidney is working
-
Check the extent of kidney damage caused by an injury or infection
-
Find an obstruction in the kidney or ureter, such as from a kidney stone
-
Find growths in the kidneys
Depending on what they are looking for, you might have multiple scans, such as a triple renal study, during the same appointment.
How a kidney scan works
A radioactive tracer substance is injected into a vein in your arm during a scan to examine kidney function. This tracer travels through the bloodstream to the kidneys, moves through the blood vessels and eventually excretes in the urine. A special camera takes pictures as the tracer moves through the kidneys. Certain patterns in the scan can reveal important information, such as:
-
Areas where the tracer collects in higher-than-normal amounts, known as "hot" spots, may indicate conditions like cancer.
-
Areas where the tracer doesn't show up, called "cold" spots, could suggest issues like blockages, cysts, scarring, infections or some cancers.
The scan also tracks how long it takes for the tracer to move through your kidneys and collect in your bladder, helping your doctor assess how well your kidneys are working.
A kidney scan can be a safer alternative to a kidney X-ray test called an intravenous pyelogram (IVP) if you're allergic to the contrast dye used in an IVP.
What to expect during the test
Before the scan, you'll need to remove any jewelry and change into a gown. Your doctor might also ask you to drink 2-3 glasses of water before the test to ensure your kidneys are well hydrated.
The exam begins with a technologist cleaning an area on your arm and injecting the radioactive tracer. In some cases, you might also receive a diuretic to increase urine output. Depending on the scan, the technologist may instruct you to lie on a table, stand or sit upright. The technologist then positions a large camera close to your abdomen to capture images while the tracer moves through your kidneys. You must remain still during the scan to ensure the pictures are clear. The camera itself doesn't emit radiation, so you won't be exposed to any additional radiation during the scan.
The test typically takes about 30 minutes, but the technologist may need to take additional images 1-2 hours after the injection. Once completed, the technologist may create a graph, called a renogram, using the data from the scan to track blood flow and kidney activity over time.
After the test
Most of the tracer will leave your body within a day through your urine or stool. It's important to flush the toilet immediately after use and wash your hands thoroughly. The amount of radiation in the tracer is minimal, so it's safe for others to be around you after the scan.
If breastfeeding, avoid nursing for 1-2 days after the test. You can use stored milk or formula during this time, but you should discard any breast milk pumped within this period.
You might notice some soreness or mild swelling at the injection site. Applying a warm, moist compress to the area can help relieve these symptoms.
Final thoughts
Your doctor will usually receive the results of your kidney scan within two days and will reach out to discuss the findings and the next steps in your treatment.
To learn more about Parkview's Lab & Diagnostic Imaging services, visit our website here.
Copyrighted material adapted with permission from Healthwise, Incorporated. This information does not replace the advice of a doctor.
