A kidney scan is a
nuclear scanning test that is done to check
kidney function or appearance.
scan to look at kidney function, a
radioactive tracer substance is injected into a vein
in the arm and then travels through the bloodstream to the
kidneys . The tracer flows through the
blood vessels in the kidneys and then is excreted into the urine. A special
camera (gamma) takes pictures of the tracer in the kidneys. This helps show
cell activity and function in the kidneys.
Many different kinds of kidney scans can be done. The types of kidney scans include a scan that looks at how blood flows to and through the kidneys, a scan that looks at the shape and size of the kidneys, and a scan that looks at how urine is made and flows out of the kidneys. Sometimes a doctor will do multiple scans at one time (for example, a triple renal study). Different radioactive tracers are used depending on what kind of scan is being done.
Areas of the kidneys where the tracer shows up
in higher-than-normal amounts, such as in some types of cancer, result in
bright or "hot" spots in the pictures. Areas where the tracer does not show up
appear as dark or "cold" spots. Cold spots can mean narrowing or blockage
of the blood vessels, pockets of fluid (cysts), some
cancers, scarring, or pockets of infection (abscesses).
The amount of time it takes for the tracer to move through the kidney, collect in
the urine, and drain into the bladder can also be seen in a kidney scan. This may be done to see how well the kidneys are working. See a picture of the
tracer in the kidneys and bladder .
A kidney scan may be done instead of a kidney X-ray test
intravenous pyelogram (IVP) for people who are
allergic to the special dye (contrast material) used during the
Why It Is Done
A kidney scan is done to:
- Check the blood flow through the kidneys.
Abnormal flow may mean narrowed renal arteries that can cause a type of high
blood pressure called renovascular hypertension.
- 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
- Find growths in the kidneys