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A magnesium test checks the level of magnesium in the blood. Magnesium is an important electrolyte needed for proper muscle, nerve, and enzyme function. It also helps the body use energy and is needed to move other electrolytes (potassium and sodium) into and out of cells.
Most of the magnesium in the body is found in the bones and inside the cells. Only a tiny amount of magnesium is normally present in the blood.
Tests for other electrolytes, such as calcium, potassium, sodium, and phosphorus, may be done along with a test for magnesium.
A test for magnesium is done to:
Many medicines may change the results of this test. Be sure to tell your doctor about all the non-prescription and prescription medicines you take. Do not take medicines containing magnesium for at least 3 days before this test. This includes antacids that contain magnesium, laxatives (such as milk of magnesia or Epsom salts), magnesium supplements, and some diuretics.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form .
The health professional drawing blood will:
The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.
There is very little risk of complications from having blood drawn from a vein.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
1.8–2.6 milligrams per decilitre (mg/dL)[0.74–1.07 millimoles per litre (mmol/L)]
1.7–2.1 mg/dL (0.70–0.86 mmol/L)
1.5–2.2 mg/dL (0.62–0.91 mmol/L)
Many conditions can change magnesium levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.
High magnesium levels may be caused by:
Low magnesium levels may be caused by:
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Current as of: December 9, 2019
Author: Healthwise StaffMedical Review: E. Gregory Thompson MD - Internal MedicineAnne C. Poinier MD - Internal MedicineAdam Husney MD - Family MedicineMartin J. Gabica MD - Family MedicineThomas M. Bailey MD - Family Medicine
Current as of: December 9, 2019
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Anne C. Poinier MD - Internal Medicine & Adam Husney MD - Family Medicine & Martin J. Gabica MD - Family Medicine & Thomas M. Bailey MD - Family Medicine
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