Serum or plasma mass concentration of a substance measured by immunoassay (e.g., protein or antibody)

What This Test Measures

The test detects the presence and quantity of a particular substance in your serum or plasma. This could include proteins like antibodies, enzymes, or other biomarkers. The method used is an immunoassay, which identifies the substance through a reaction with antibodies or other specific binders.

Why It’s Done

Your healthcare provider may order this test to diagnose or monitor conditions such as infections, autoimmune diseases, kidney or liver function, or other systemic issues. It may also be part of routine screening or follow-up care.

Common Uses

This test is often used to detect abnormal levels of substances that may indicate health problems. For example, it could help identify immune system disorders, protein abnormalities, or responses to medications.

Sample Collection and Preparation

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma, which is sent to the lab for testing. No special preparation is needed, but fasting may be required depending on the specific test.