What is Serum Concentration?

Blood tests are an important diagnostic tool in the medical world. Through testing, doctors can measure the amount of a chemical, compound or other substance present in a person’s body and circulating through the blood. Not every substance is present in every part of the blood. Serum concentration is the measure of a compound found in the blood's liquid.

Human blood is made up of two components: blood cells and plasma. Blood cells contain white and red blood cells. Red cells carry oxygen throughout the body while white cells fight infection. Plasma is composed of minerals, proteins and clotting factors. Blood serum is plasma that has been modified to remove the clotting factors.

When doctors run a serum concentration test, they collect blood from the body and run it through a centrifuge, which spins the sample at a rapid speed. The spinning separates the blood into three distinct parts. The blood cells sink to the bottom of the tube, while the serum rises. A thin layer of white blood cells separates the blood cells and serum.

Human serum can be tested to uncover an ailment. Serum glucose is a serum concentration test measuring the amount of glucose, or blood sugar, in a person’s system and can rule out or uncover a diagnosis of diabetes. A serum ferritin test measures iron and is used in the diagnosis of anemia. Serum concentration tests measure biological serum for specific amounts of these and other compounds. The serum levels are then compared to established standards to determine whether the test result is elevated serum concentrations or lower serum levels than the standard.

In some cases, serum concentration is used to identify a person through blood type. Blood types are a measure of certain antigens in the blood. The measure of a mineral within the blood can also determine whether a medication is performing properly. A person taking a thyroid drug might need a regular serum calcium test to ensure the drug is pushing the body to maintain appropriate levels of the mineral.

Serum concentration can also be used as a measure of immunity. A serum antibody test measures the amount of antibodies in the system against a certain disease, such as the flu or rabies. The most common immunity test is the serum ELISA (enzyme linked immunosorbent assay) test. The ELISA test incubates a medical serum sample in order to isolate specific, disease-linked serum components.