Methylene blue test
Key points
- 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).
- An angiocatheter will be placed in a vein, typically from the inside of the elbow or the back of the hand.
- The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust.
- When the needle is inserted, you may feel moderate pain or a stinging sensation.
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.
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- School age test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
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.
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.