Serum or Plasma Substance Concentration by Immunoassay (e.g., for a specific protein or hormone)

What This Test Measures

The test detects the concentration of a specific substance (e.g., a protein, hormone, or enzyme) in your serum or plasma. The exact substance depends on the clinical indication, such as monitoring thyroid function, detecting infections, or evaluating metabolic disorders. The method used is typically an immunoassay, which identifies and quantifies the substance with high sensitivity and accuracy.

Common Uses

This type of test is commonly used to diagnose or manage conditions like hormone imbalances (e.g., thyroid disorders), infections (e.g., viral markers), or diseases affecting protein synthesis (e.g., liver or kidney conditions). It may also be used in research or specialized clinical settings for rare or niche biomarkers.

Sample Collection and Preparation

Blood is drawn from a vein in your arm, and the sample is processed to separate serum (if clotted) or plasma (if anticoagulated). The test then analyzes the fluid for the target substance using immunoassay techniques, which may involve antibodies binding to the substance to measure its concentration.

When You Might Need This Test

Your healthcare provider may recommend this test if you have symptoms or risk factors for conditions linked to the substance being measured, such as unexplained fatigue, weight changes, or abnormal lab results from other tests. It may also be part of routine monitoring for chronic conditions.