Methylene blue test

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Methylene blue test

Definition:

The methylene blue test is a test to determine the type of methemoglobinemia an affected person has, based on the responsiveness of blood methemoglobin to the administration of methylene blue (a dark green powder that can turn methemoglobin back into normal hemoglobin).

How the test is performed:

An angiocatheter will be placed in a vein, typically from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood).

A needle is inserted into the vein to allow placement of the angiocatheter. The needle is then removed while the angiocatheter is left in the vein. The tourniquet is then removed to restore circulation.

Methylene blue is then injected into the vein.

How to prepare for the test:

No special preparation is required for this test.

How the test will feel:

When the needle is inserted, you may feel moderate pain or a stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

Methemoglobinemia has several causes, many of which are genetic. This test assists in distinguishing between methemoglobinemia caused by a deficiency of NADH cytochrome b5 reductase and certain types of hereditary methemoglobinemia caused by hemoglobin M disease.

Most methemoglobinemia quickly responds to IV administration of methylene blue, and can be controlled by daily doses of oral methylene blue and ascorbic acid. However, some types of hereditary methemoglobinemia do not respond to methylene blue. This test allows distinction between the two and helps your health care provider develop a plan of care.

Review Date: 10/27/2004
Reviewed By: Celeste Krauss, M.D., Board Certified Clinical Genetics, Clinical Cytogenetics, Pediatrics and a Founding Fellow, of the American College of Medical Genetics. Review provided by VeriMed Healthcare Network.

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