Serum or plasma concentration of a substance (unspecified analyte) measured by immunoassay

Why This Test Might Be Ordered

Your healthcare provider may order this test if they suspect you have an infection, an autoimmune condition, a metabolic disorder, or if you’re experiencing symptoms like fatigue, fever, or unexplained weight changes. It can also be used to monitor treatments for conditions like cancer, liver disease, or kidney problems.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm to draw blood. This usually takes a few minutes. Avoid eating or drinking for a short period before the test if your provider specifies it. Stay hydrated and rest if you feel lightheaded during the procedure.

What the Test Results Mean

Results will show the concentration of the measured substance in your blood. High or low levels may indicate an underlying health issue, but results alone aren’t diagnostic. Your provider will interpret the results in the context of your symptoms and medical history.

Common Conditions Monitored

This test can help identify or track conditions such as infections (e.g., viral or bacterial), immune disorders (e.g., lupus, rheumatoid arthritis), or certain cancers. It may also be used to monitor medications or metabolic processes.