Serum/plasma concentration of a substance measured by immunoassay (e.g., antibody screening)

What This Test Measures

This test measures the level of specific antibodies in your serum or plasma. Antibodies are proteins produced by your immune system in response to infections, vaccines, or other triggers. The test may identify whether your body has detected and fought off a pathogen, or if there is an ongoing immune response to a condition like lupus, rheumatoid arthritis, or an infection.

Common Uses

Screening for infections (e.g., viral, bacterial, or parasitic), detecting autoimmune diseases (e.g., lupus, rheumatoid arthritis), evaluating immune system function, or confirming exposure to certain substances (e.g., toxins, vaccines).

How the Test Works

Blood is drawn and processed to separate serum or plasma. The sample is then analyzed using an immunoassay method, which detects and quantifies specific antibodies bound to a target antigen. This process may involve color changes, fluorescence, or other signals captured by the lab equipment.

Sample Collection and Preparation

A small amount of blood is collected via a needle, typically from a vein in your arm. The blood is then processed to remove cells, leaving behind serum or plasma. This liquid is stored and sent to the lab for testing.