Definition & Overview

A non-imaging radioisotopic kidney function test is a diagnostic procedure that uses nuclear medicine technology to examine a person’s kidney using radiopharmaceuticals. Radiopharmaceuticals are molecules or chemicals that are attached to a radioactive isotope, which targets the kidneys to provide essential information to help doctors make a diagnosis.

The test is an invaluable tool in diagnosing kidney diseases because it can provide information that other diagnostic tools cannot.

Who Should Undergo and Expected Results

A non-imaging radioisotopic kidney function test can help diagnose patients who are suspected of suffering from various problems affecting the kidneys. These include:


Patients suffering from some chronic diseases are also at an increased risk of kidney problems. Thus, they may also benefit from a kidney function study. These include those who suffer from:

  • Diabetes
  • High blood pressure
  • Cardiovascular disease
  • Heart failure
  • Enlarged prostate


Patients with close relatives who suffer from kidney disease may also need to undergo kidney function testing to assess their risk.

There are many types of kidney function tests, and non-imaging radioisotopic study is one of them. A kidney function study helps diagnose diseases by evaluating how the kidneys function. They can determine or measure:

  • How much a person urinates
  • The level of urea, creatinine, and some dissolved salts present in the urine


Most patients undergo a non-imaging radioisotopic kidney function study upon the recommendation of a general practitioner (GP). They usually do so when they show signs and symptoms of kidney problems, such as the following:

  • Nausea
  • Vomiting
  • Fatigue
  • Weakness
  • Loss of appetite
  • Sleeping problems
  • Muscle cramps
  • Frequent urge to urinate
  • Painful urination
  • Fluid retention
  • Bloody urine


A radioisotopic study offers several advantages over other diagnostic methods, such as exploratory surgery. These include the following:

  • It provides functional information that cannot be obtained using other diagnostic methods.
  • It is less traumatic than exploratory surgery.
  • Allergic reactions to the radioisotope material used in the study are extremely rare when compared to contrast dye materials used in other imaging tests.


However, diagnostic tests using nuclear medicine are more time-consuming than other diagnostic scans. This is because it takes time for the radiopharmaceutical to make its way to the kidneys. Most tests take up to three hours to be completed.

The results of the test are interpreted by a physician with special training in nuclear medicine. The final test results may take a few days to be delivered to the patient’s GP.

How is the Procedure Performed?

For the procedure, a small amount of a radiopharmaceutical is administered into the patient’s body. This can be done through an intravenous injection, through swallowing or ingestion, or through inhalation. In a non-imaging study, the radioisotope is commonly injected into a vein. The radiopharmaceutical used in the study is naturally attracted to the kidneys. Once in the kidneys, the radioactive isotope material releases small amounts of radiation.

If the test involves imaging, the radiation energy emitted by the radioisotope can be detected from outside the body using special gamma cameras. The cameras use this to record the location and movement of the radioisotope and to create a two-dimensional and three-dimensional image of the kidneys. The images are then evaluated to form a diagnosis.

In a non-imaging radioisotopic study, the procedure does not involve the use of special cameras. Once the radiopharmaceutical is administered into the body usually through injection, the doctor will take blood and urine samples from the patient. The results of blood and urine tests will then be used to analyse kidney function and make a diagnosis, which will guide the doctors in determining the appropriate course of treatment for the patient.

No special preparations are needed for this procedure. Patients will not be asked to undress, but they do need to remove any metal objects.

During a non-imaging test, patients are also allowed to leave the hospital or clinic after the injection, as long as they come back at the correct time to have their blood and urine samples collected.

Possible Risks and Complications

Despite the many advantages of a non-imaging radioisotopic kidney function test, it is still associated with certain risks. These include the following:

  • The test exposes patients to small doses of radiation. The doses, however, are very small, so they are not associated with any long-term adverse effects. The dosage is similar to that used during an x-ray scan.
  • It is not advisable for pregnant women. All tests involving radiation should only be used when their potential benefits outweigh their risks.
  • Although rare, allergic reaction to the radioisotope material is still possible. However, within the five decades that diagnostic nuclear medicine has been used, such reactions have been extremely rare.

    References:

  • “Diagnostic nuclear medicine.” Poole Hospital NHS Foundation. https://www.poole.nhs.uk/a-z-services/n/nuclear-medicine/diagnostic-nuclear-medicine.aspx

  • Chrispin AR, Gordon I, Hall C, Metreweli C. “Diagnostic imaging of the kidney and urinary tract in children.” https://books.google.com.ph/books?id=pZoyBwAAQBAJ&pg=PA59&lpg=PA59&dq=Kidney+Function+Study,+Non-Imaging+Radioisotope+Study&source=bl&ots=Rd6VphglL0&sig=fzrWxt54zwfrXheZWk-WcvDr5S8&hl=en&sa=X&redir_esc=y#v=onepage&q=Kidney%20Function%20Study%2C%20Non-Imaging%20Radioisotope%20Study&f=false

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