A serum magnesium test is a measurement of how much magnesium there is in the blood.
Blood is most often drawn from a vein. The vein usually used is on the inside of the elbow or the back of the hand.
The procedure is done in the following way:
For infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. Afterward, a bandage may be placed over the area if there is any bleeding.
No special preparation is needed.
When the needle is inserted to draw blood, you may feel slight pain, or a prick or stinging. Afterward, there may be some throbbing.
This test is done when your health care provider suspects you may have an abnormal level of magnesium in your blood.
About half of the body's magnesium is found in bone. The other half is found inside cells of body tissues and organs.
Magnesium is needed for nearly all chemical processes in the body. It helps maintain normal muscle and nerve function, and keeps the bones strong. Magnesium is also needed for the heart to function normally and to help regulate blood pressure. Magnesium also helps the body control blood sugar level and helps support the body's defense (immune) system.
1.7 to 2.2 mg/dL
Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.
A high magnesium level may indicate:
A low magnesium level may indicate:
There is very little risk in having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks may include:
Magnesium - blood
Klemm KM, Klein MJ. Biochemical markers of bone metabolism. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 15.
Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 225.
Updated by: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.
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