Abnormal levels of magnesium are most frequently seen in conditions or diseases that cause impaired or excessive excretion of magnesium by the kidneys or that cause impaired absorption in the intestines. Magnesium levels may be checked as part of an evaluation of the severity of kidney problems and/or of uncontrolled diabetes and may help in the diagnosis of gastrointestinal disorders.
Since a low magnesium level can, over time, cause persistently low calcium and potassium levels, it may be checked to help diagnose problems with calcium, potassium, phosphorus, and/or parathyroid hormone (involved with calcium regulation).
Magnesium levels may be measured frequently to monitor the response to oral or intravenous (IV) magnesium supplements and may be used, along with calcium and phosphorus testing, to monitor calcium supplementation.
Magnesium testing may be ordered as a follow-up to chronically low levels of calcium and potassium. It also may be ordered if you have symptoms of an abnormally low magnesium level such as muscle weakness, twitching, cramping, confusion, cardiac arrhythmias, and seizures.
Although dietary deficiencies of magnesium are rare, your doctor may order a magnesium level to check for a deficiency as part of an evaluation of malabsorption, malnutrition, diarrhea, or alcoholism. If you are taking certain medications that can cause the kidneys to excrete magnesium, testing may be performed as well. If magnesium and/or calcium supplementation is necessary, then the magnesium blood level most likely will be checked at intervals to monitor the effectiveness of treatment.
If you have a kidney disorder or uncontrolled diabetes, your doctor may order magnesium levels to help monitor kidney function and to make sure that you are not excreting or retaining excessive amounts of magnesium.
What does the test result mean? NOTE: This test has no single number that identifies an abnormal result.
Your lab report (see a sample report) should include
a range of numbers (reference range) that identifies what is expected for you based on
your age, sex, and the method used in that laboratory. You can find more information
about expected results at Reference Ranges
and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.
Low levels of magnesium (hypomagnesemia) in your blood may mean that you are: 1) not getting enough magnesium in your diet; 2) your intestines are not absorbing enough magnesium; or 3) your kidneys are excreting too much magnesium. Deficiencies may be due to:
Low dietary intake (seen in the elderly, malnourished, and with alcoholism)
Gastrointestinal disorders (such as Crohn’s disease)
Increased levels of magnesium are rarely due to dietary sources but are usually the result of an excretion problem or excessive supplementation. Increased levels are seen in:
This article was last reviewed on November 17, 2006.
This page was last modified on April 8, 2009.
The review date indicates when the article was last reviewed from beginning to end to ensure that it reflects the most current science. A review may not require any modifications to the article, so the two dates may not always agree.
The modified date indicates that one or more changes were made to the page. Such changes may or may not result from a full review of the page, so the two dates may not always agree.
