Renal Captopril Scan

A Renal Captopril scan is a simple and painless way of taking pictures of the blood flow and function of your kidneys using a radioactive tracer. This test is requested by your physician to determine if your high blood pressure is caused due to the narrowing of the arteries supplying blood to the kidneys. 

This test can be performed as either one day or a two-day procedure. Our booking office will provide you with information about your appointment times. When you arrive in the department, a technologist will explain the entire procedure to you and then give you the opportunity to ask any questions.

One day protocol: (approximately 4 hours)

You will be given three appointments for your test:

Part 1 (1 hour): The technologist will ask you to lie down on an imaging table and place you under a special detector, called a gamma camera. The technologist will then inject a radioactive tracer into a vein in your arm. There are no known side effects from this injection. The technologist will then take a series of images of your kidneys. The imaging will take about 45 min. Upon completion of this part, you will be free to go for approximately 1 hour. You will need to continue fasting during this wait. The technologist will give you a return time before you leave.

Part 2 (1 hour): When you return, the technologist will take your blood pressure, and have you swallow a pill called captopril, which is needed for the study. They will continue to take your blood pressure approximately every 15 minutes over a 60 min period.

Part 3 (1 hour): Part one is repeated. Upon completion, you can return home with no ill effects.

Two-day protocol: (approximately an hour each day)

In this case, part 1 will be performed on one day (no fasting required) and parts 2 and 3 (you will need to fast for 4 hours) will be performed on another day.  

• Bring your Health card.
• You should arrive well hydrated by drinking at least 0.5 liters of water starting one hour before your appointment. You may empty your bladder as required.  
• You need to fast for 4 hours prior to the test.
• Certain drugs may interfere with this study and these should be discontinued prior to the procedure. The clerk who books your test will ask you for a complete list of the medications that you are taking. It is important that you also bring your list of medications to your first appointment. Please consult your physician before stopping any medication.  
• Please leave all valuables at home.
• Please notify our booking office at the time of scheduling your appointment if you have any concerns regarding claustrophobia, lying still, require a mechanical lift for transfer to the imaging bed, have a language barrier or any other special needs, so that appropriate arrangements can be made ahead to provide you with the best possible care.

Only the pinprick of the injection needle may hurt a bit. You may have had a blood test in the past. This is much the same. 

The injection contains a small amount of radioactive tracer which emits gamma rays (these are similar to X-rays). The radiation dose is very low and will disappear by itself after two days. The results of your scan will give your doctor useful information about your condition and will help them plan your treatment. The benefits of having the scan far outweigh any potential risk from the small radiation dose.  

No special precautions are needed after the scan. If you are travelling across any borders in the seven days after your scan, please ask us for further advice. Border crossings and airports have very sensitive radiation detectors which may pick up tiny amounts of radioactivity remaining after your scan. We will give you a letter that you can show to customs officials at border crossings or airports. 

Please tell us if you are pregnant or breastfeeding.

Breastfeeding must be interrupted for up to 4 hours after the exam, during which time one milk meal should be pumped and discarded. Prepare for your exam accordingly. 

A specially trained doctor will examine the results of your test. This is normally done soon after the end of the test. A report is then sent to the doctor who asked us to do the test. Your doctor will normally receive the report within one week. You will also have access to the report on MyChart as soon as it is released. 

If you have questions about the scan results or report, please contact your doctor directly. They are best able to interpret the report for you. 

No. This test is paid for by the healthcare system. The test costs several hundred dollars, so please notify the department at 613-761-4831 if you cannot make your appointment. 

If you cannot make your appointment, it is important that you notify the department at 613-761-4831 as soon as possible. Failure to make your appointment results in wasting of expensive materials that are ordered especially for your appointment and also reduces availability to other patients. Missed appointments may also result in delays of your treatments.