Blood plasma is a yellowish liquid that serves as a suspension material for blood cells. It is primarily made of water, but also contains proteins, salt and glucose. Plasma transports a range of materials from cellular waste products to amino acids, ions and antibodies. Many blood tests are in fact plasma blood tests, in which the plasma is tested exclusive of red blood cells.
Plasma blood tests require a sample of blood, usually drawn with a needle. The blood is then treated with an anti-coagulant, which stops clotting, and then it is run through a centrifuge to separate the blood and plasma.
Plasma blood testing can be used to determine HIV infection by detecting HIV antibodies in the plasma.
The Center for Disease Control uses plasma blood testing to confirm a number of conditions including toxocariasis and toxoplamosis (conditions caused by parasites).
Plasma glucose tests, which measure blood sugar levels, are used as a diabetes screening test.
Plasma travels to virtually every part of the body, which means it is exposed regularly to any infections. This is the reason why plasma testing is used across so many situations.