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Alternative names Return to top
Mg+2Definition Return to top
This is a test that measures the amount of magnesium in the blood.How the test is performed Return to top
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and cause veins below the tourniquet to distend with blood. A needle is inserted into the vein, and the blood is collected in an airtight vial or a syringe.
During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test Return to top
There is no special preparation for this test.
Infants and children:
The physical and psychological preparation involved in readying a child for any test or procedure depends on the child's age, interests, previous experiences, 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:
How the test will feel Return to top
When the needle is inserted to draw blood, some people may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.Why the test is performed Return to top
This test is performed when an abnormal blood level of magnesium is suspected.
About half of the body's magnesium is found in bone, where it plays a structural role (along with calcium, phosphate, and various proteins). In all other tissues magnesium is among the most abundant of all the intracellular (inside the cell) electrolytes, second only to potassium.
Magnesium is necessary for essentially all biochemical processes. For example, synthesis and use of ATP (the major source of energy for all cells).
Normal Values Return to top
1.8 to 3.0 mg/dLWhat abnormal results mean Return to top
High magnesium levels may be seen with the following conditions: Low magnesium levels may be seen with the following conditions:What the risks are Return to top
Special considerations Return to top
Veins and arteries vary in size from one patient to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others. Update Date: 5/4/2003 Updated by: Bridget Martell, M.D., Department of Internal Medicine, Albert Einstein College of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |
