Paediatric MAG3 Renal Scan Information Sheet

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What is a MAG3 Renal Scan?

A MAG3 scan shows us how well the kidneys are functioning, including whether one works harder than the other, if one is not getting as much blood, and if there are any blockages. The tracer we use is filtered from the bloodstream by functioning kidney tissue, and then excreted into the bladder.

What preparation is required?

There is no specific preparation for this test – your child does not need to fast, or skip any medications. We recommend keeping your child well hydrated for the whole day of the test. This helps to improve the images as well as lower your child’s radiation dose.

What happens during the test?

Your child will be given a small injection of a radioactive tracer, usually into a vein in the arm, or sometimes the foot. Imaging begins immediately, as the kidneys start to filter the blood within a minute after injection. These images go for 30min. We then usually give an injection of ‘Lasix’, which forces the kidneys to work harder. We take more images for 30min after this. This helps to diagnose any serious blockages in the tubes leaving the kidneys. Sometimes we need a delayed image about 4hrs after your injection.

Are there any side effects?

There are no side effects from the tracer injection, and no restrictions following the test. The amount of radiation used is quite small, and scaled down, based on height and weight.

How long will the test take?

Please allow about 90min for the whole test. If we need you to return for delayed images, they will only take 5min.

For paediatric patients:

Please don’t apply any EMLA cream to your child. We perform these tests on young children every week, and our Nuclear Medicine Scientists are trained to perform these injections with a minimum of fuss and the smallest needle available. EMLA usually makes veins harder to find, making our job considerably harder. Most children do not experience much discomfort from the needles we use, without any anaesthetic cream. This is our preference; however please feel free to call us if you have any questions or concerns.


It is important to bring any previous test results and your Medicare card with you.

Please feel free to call us on 6244 2439 if you have any questions or to reschedule.


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