Serum or Plasma Substance Concentration by Immunoassay (e.g., for C-reactive protein or similar inflammatory marker)

What This Test Measures

This test detects specific proteins in your serum or plasma that are produced in response to inflammation or immune activity. The exact proteins measured depend on the lab’s specific panel, but they often include markers like C-reactive protein (CRP) or others that reflect your body’s reaction to injury, infection, or disease.

Why It’s Done

Your healthcare provider may order this test to evaluate symptoms such as fever, joint pain, swelling, or unexplained fatigue. It can also be used to monitor chronic conditions like arthritis, heart disease, or infections.

Common Uses

Common reasons include diagnosing infections (e.g., bacterial or viral), checking for autoimmune diseases (e.g., rheumatoid arthritis), assessing heart attack risk, or monitoring treatment progress for conditions like lupus or kidney disease.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is then processed to separate serum (liquid part after clotting) or plasma (liquid part after anticoagulant use). The test analyzes these fluids for protein markers.