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MAG 3 Lasix Renal Scan

A MAG 3 Lasix renal scan (Lasix scan) is a nuclear medicine test that provides images of the kidneys to look for kidney function, size, shape, position and blockage of urinary flow. There are no dietary or activity restrictions before or after the test. The test may take up to two hours to complete so families are encouraged to bring toys and books to help entertain the child.

What is a Lasix renal scan?

A MAG3 (Mercaptuacetyltriglycine) Lasix renal scan is a nuclear medicine test that provides images of the kidneys to help determine their level of functioning and if there are any obstructions. They can be very important in the diagnosis of hydronephrosis and UPJ obstructions. The test uses Technetium-99m MAG3, a radioisotope, which is injected through an IV into the child. A special camera is then used to take photos of the kidneys.

The tracer is put into the urine and can be followed as it goes down into the bladder. In patients who have any blockage or obstruction in the urinary tract, the test shows that the tracer does not drain. This test can take up to an hour and a half.

What happens during a renal MAG3 scan?

  1. To perform the examination, an IV is placed in one of your child’s veins by a specialist.
  2. A Foley Catheter is inserted by a nurse specializing in pediatrics into the child’s bladder through their meatus (the opening where urine exits the body). The catheter keeps the bladder empty of urine during the test. And will be removed when the test is completed.
  3. The radiology technician injects the radioisoptope through the IV and the large camera will be used to take images of the kidneys. The imaging takes place intermittently for about 20 minutes. After this time period a diuretic, called Lasix is given to the child through the same IV. The diuretic causes the kidneys to produce more urine than normal during a small period of time. More images are taken at this point as well. Once all the images have been taken the IV and the catheter are removed.

Is a MAG3 Lasix renal scan safe?

At CHOC Children’s we are committed to exposing our patients to the lowest doses of radiation possible for every procedure.

  • Nuclear medicine has been used on infants and children for over 40 years with no known adverse effects from the low doses employed.
  • Technetium-99m MAG3 has a tiny amount of radioactive molecules in it.
  • The camera used to obtain the images does not produce any radiation.

How do I learn the results of the renal MAG3 scan?

Once your test has been completed here at the Center, the child’s family will be notified with the results within two weeks. If you have not heard from our office with test results, please call us at 714-509-3919. If your study was done at a different facility please contact our office upon its completion so we may obtain the results to review for you.

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UC Irvine

CHOC Children's is affiliated with the UC Irvine School of Medicine