Magnesium helps the body use and make and is needed to move potassium and sodium into and out of cells.

A test for magnesium is done in order to:

• Find a cause for nerve and muscle problems, such as irritability, muscle twitches, and muscle weakness.
• Find the cause of symptoms, such as low blood pressure, nausea, diarrhea, dizziness, vomiting, muscle weakness, and slurred speech.
• Find the cause of trouble breathing or heart problems, especially in people who have kidney disease.
• Find the cause of a low potassium or calcium level that is not improving with treatment.
• Look for changes in magnesium levels caused by medicines, including diuretics.
• Check if those with heart problems need extra magnesium. Low magnesium levels may increase the chances of life-threatening heart rhythm problems.
• Measure magnesium levels when it is being given for medical treatment.