COVID-19 information for patients and families

To help protect our people, patients and communities, we are screening everyone who enters our main hospital buildings. Some of our entrances may be closed or have reduced access.

Please check our COVID-19 information page for more updates before coming to our sites.

Medical Imaging

Nuclear Medicine > Exams & Procedures > Renal Captopril Scan

This scan tests the level of function of each kidney, looking specifically for differences in blood supply (i.e. renal artery stenosis vs renovascular hypertension).

This test involves pre-treatment with Captopril, a drug that prevents the constriction of the arteries supplying the kidneys. A capsule of Captopril will be given one hour before the pictures. Your blood pressure will be monitored for any changes caused by the Captopril. You will receive an injection of a radioactive tracer into your vein, which will flow through the bloodstream and be filtered out by the kidneys. Pictures are taken continuously from the time the tracer is injected for half an hour. At the end of the hour you are asked to use the washroom and then a one-minute picture is taken.


  • You should have nothing to eat for at least four hours before the test.
  • You should drink plenty of water prior to the test and use the washroom immediately before the test begins.
  • Some medications interfere with this test. Please consult your doctor about which medications to stop before the test.
  • Bring a list of all medications and supplements you take. This includes vitamins, herbal remedies, and holistic medications.
  • Do not bring children or pregnant women with you to the department. We do not want to expose them to unnecessary radiation.
  • Any of these procedures is subject to change according to the nuclear medicine physician. The duration of the tests is a rough estimate. Please be aware that the time may be lengthened if a scan has to be repeated, if emergency cases are brought to the department or due to unforeseen circumstances.

About the Procedure

  • The procedure takes about one and a half hours.
  • A technologist will briefly explain the test to you and try to answer any questions you may have about the procedure.
  • A technologist will ask you a few questions about your medical history and medications.
  • You will be given a 25 milligram capsule of Captopril and wait 45 minutes. We will monitor your blood pressure for the next hour.
  • You will be asked to use the washroom immediately before the pictures are started.
  • You will be asked to lie down on an imaging bed.
  • A camera will be positioned below you (above you if you have had a kidney transplant).
  • The technologist will give you an injection of a radioactive tracer into a vein.
  • Pictures are taken as the tracer is injected and for the next 30 minutes. It is very important that you do not move during these pictures.
  • At the end of the 30 minutes you will be asked to use the washroom.
  • You will be repositioned above the camera and a one-minute picture will be taken.