Serum or plasma concentration of a substance measured by immunoassay (e.g., tetramethylbenzidine-based chemiluminescent immunoassay)

What This Test Measures

The test detects the presence and amount of a particular substance in your serum or plasma. Immunoassays like this one use antibodies to bind to the target substance, triggering a measurable reaction (often involving a color change or light detection). This helps determine if your blood contains abnormal amounts of the substance.

Why It Might Be Ordered

Your healthcare provider may order this test to diagnose or monitor conditions related to the specific analyte being tested. For example, it could be used to check for infections, autoimmune diseases, or certain metabolic disorders.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate serum (if clotted) or plasma (if anticoagulated) for testing. This sample is then sent to a lab for analysis.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a certain period if your provider specifies it. Avoiding certain medications or foods for a few days before the test can improve accuracy.