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What is a renal/kidney scan?

A renal scan also referred to as a kidney scan or renal scintigraphy, is a type of nuclear imaging test that helps in determining the size, shape and functioning of kidneys. It also aids in checking the blood flow through kidneys. This technique involves the use of a small amount of radioactive material, also called radioactive tracer, which is absorbed by kidney tissues and emits gamma rays. These gamma rays are then absorbed by the scanner and are used to create an image of kidneys.

Some tissues in kidneys absorb more tracer, whereas others absorb less. The tissues with more amount of tracer appear brighter and are called hot spots, whereas tissues with less amount of the tracer appear less bright and are called cold spots.

  1. Why is renal/kidney scan performed?
  2. How do you prepare for renal/kidney scan?
  3. How is renal/kidney scan performed?
  4. What do renal/kidney scan results mean?

A kidney scan is performed in individuals suspected to have abnormal kidney functions or those who need surgery for a kidney problem. It is recommended for the diagnosis or assessment of:

It is useful in individuals who are sensitive or allergic to the contrast dye used in other imaging techniques.

No special preparations like fasting are needed before a kidney scan. No medicines are needed for relaxation or sedation. However, additional water intake before the test may be recommended. The individual would be asked to empty their bladder before beginning the test. The doctor should be informed about the following conditions before the test to avoid any complications:

  • Pregnancy or expected pregnancy as this test involves radiation exposure, which is harmful to the foetus
  • Allergy to any substance such as medicines, contrast dyes, iodine or latex
  • Medicine especially anti-hypertensive medications may interfere with test results

Kidney scan may be done as an outpatient procedure or it may need hospitalisation.  The process of kidney scan is as follows:

  • You will be asked to wear a hospital gown and remove any jewellery and accessories
  • Radioactive material will be injected intravenously through your arm. The needle prick may cause a bit of discomfort to some people
  • You will then be made to lie on a table or sit straight, and images of kidneys will be taken for about 30 minutes
  • The entire procedure takes about 40 minutes. The doctor will remove the intravenous line after the imaging is complete.

The radioisotope used for kidney scan has no side effects, and it will cause no discomfort. It will not be felt like something different except for a slight metallic taste in the mouth for a moment.

In certain cases, the doctor may recommend the use of a diuretic during the scan. This will prolong the duration of the procedure to about 60 minutes. The diuretic will be given halfway through the scan and the imaging will then be continued. You will be told to empty your bladder after the test, and an additional image will be taken for a minute.

Although this test is safe, the radioactive material releases some amount of radiation, which takes about 24 hours to be eliminated from the body. Therefore, caution is advised in pregnant women and lactating mothers.

Some people may be allergic to the radioisotope, and when not treated in time it may lead to anaphylaxis; however, such occurrences are rare.

A radiologist will interpret the image of the scan and provide the report in less than 24 hours of the scan.

An abnormal result on the scan may be due to the following underlying conditions:

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor. 

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  1. Cleveland Clinic. [Internet]. Cleveland, Ohio. Renal Scan
  2. University of Rochester Medical Center Rochester, NY. [Internet] Kidney Scan
  3. Penn State Health; Milton S. Hershey Medical Center; Pennsylvania, USA. Renal scan. [Internet]
  4. Cynthia C. Chernecky, Barbara J. Berger. Laboratory Tests and Diagnostic Procedures. Elsevier; Saunders, 1997
  5. Richard J. Johnson, John Feehally, Jurgen Floege. Comprehensive Clinical Nephrology . Elsevier; Published Date: 23rd August 2018
  6. Osama M. Sarhan. Posterior urethral valves: Impact of low birth weight and preterm delivery on the final renal outcome . Arab J Urol. 2017 Jun; 15(2): 159–165. PMID: 29071146