Red blood cell magnesium test

Red blood cell magnesium is a test that measures the concentration of magnesium inside red blood cells. This is thought to be a more reliable test than serum magnesium as very little of the body's magnesium is found in the serum. 99% of total magnesium is found bone, muscles and non-muscular soft tissue.

serum The clear yellowish fluid that remains from blood plasma after clotting factors have been removed by clot formation. (Blood plasma is simply blood that has had its blood cells removed.)