Magnesium (serum magnesium)

What this test is

Magnesium helps your muscles, nerves, and heart work well. Most people get enough from food. Some medicines can lower your magnesium over time. These include long-term acid-reducing drugs and water pills. Checking it makes sense if you take one of these. It also makes sense with a low potassium or calcium level that has no clear cause. So is an irregular heartbeat. There is also a version of this test called 'RBC magnesium.' It is not a proven test. There is no clear proof it beats the regular blood magnesium test. If you have no drug or symptom pointing to low magnesium, you usually do not need this test as part of a general check-up.