A magnesium test is used to measure the amount of magnesium in your blood.

Magnesium is a metallic element mainly found in the bones and is essential to life.

Abnormal magnesium levels can occur in conditions that affect the functioning of your kidneys or intestines.

A magnesium test may be recommended as part of a series of tests if you have symptoms such as nausea, weakness, twitching, cramping or cardiac arrhythmia (irregular heartbeat). 

You may have abnormally low levels of magnesium, calcium or potassium in your blood.

Read more about the magnesium test on Lab Tests Online UK.