Does this test have other names?
What is this test?
This test measures the amount of the mineral magnesium in your blood. Magnesium is
found in your cells and bones. It's necessary for many different chemical reactions
in your body. Your heart needs magnesium to beat properly. Your muscles need magnesium
to contract and relax. Your nerves need magnesium to send signals. Magnesium also
plays a role in controlling blood sugar and blood pressure. Your body uses magnesium
to absorb calcium.
Why do I need this test?
You may have this test if you have signs and symptoms that might be caused by too
much or too little magnesium. These can include:
You may also have this test if you have kidney problems, diabetes, alcoholism, or
some other conditions, or if other blood tests show you have abnormal levels of other
minerals, such as calcium, potassium, or phosphorus.
If you are pregnant, your healthcare provider may watch your magnesium levels to make
sure you don't develop preeclampsia. This is a serious complication marked by protein
in your urine and high blood pressure.
What other tests might I have along with this test?
You may have other blood tests to measure levels of other minerals or substances in
your blood. You may also have a test to check for magnesium in your urine.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Results are given in milliequivalents per liter (mEq/L). Normal test results are:
1.3 to 2.1 mEq/L for adults
1.4 to 1.7 mEq/L for children
1.4 to 2 mEq/L for newborns
Abnormal magnesium levels may have many possible causes. For example, increased levels
of magnesium may be seen with kidney disease because magnesium is excreted by the
kidneys. A low magnesium level can be a sign of diabetes, some digestive problems,
malnourishment, or long-term (chronic) alcoholism. Lower magnesium levels during pregnancy
may mean preeclampsia.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Some medicines such as antacids and laxatives can cause magnesium levels to rise.
Medicines such as some antibiotics, insulin, and water pills (diuretics) can cause
magnesium levels to drop.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.