Serum or plasma substance concentration (e.g., protein) measured by immunoassay

What This Test Measures

This test identifies the presence and amount of particular proteins or substances in your serum or plasma. The method used is typically an immunoassay, which detects specific molecules (such as antibodies, enzymes, or hormones) based on their unique chemical properties. The result helps identify or confirm conditions like kidney disease, infections, or autoimmune disorders.

Why It’s Done

Your healthcare provider may order this test to diagnose, monitor, or manage health issues such as kidney function, inflammation, or immune system activity. For example, it could help assess proteinuria (protein in urine), detect certain infections, or evaluate immune responses.

Common Uses

Common reasons for this test include diagnosing kidney disease, checking for infections (e.g., viral or bacterial), monitoring autoimmune conditions, or evaluating protein levels in blood or urine. It may also be used in research or specialized clinical settings to identify rare or specific biomarkers.

What to Expect Before the Test

No special preparation is usually needed unless instructed by your doctor. You may be asked to fast for a certain period if the test involves fasting-related substances. Bring any medications or supplements you’re taking to your appointment.