A magnesium blood test measures the amount of magnesium in your blood. Magnesium is an essential mineral that helps support muscle and nerve function, heart rhythm, and normal energy production.
The test may be ordered to check for low or high magnesium levels, particularly when symptoms such as muscle cramps, weakness, irregular heartbeat, or abnormal electrolyte levels are present. It may also be used to monitor magnesium levels during certain medical treatments or in people with conditions affecting magnesium balance.