: Leukocyte Esterase, Serum or Plasma

: What Is Leukocyte Esterase?

: Leukocyte esterase is an enzyme produced by neutrophils, a type of white blood cell. Its presence suggests that white blood cells are active or breaking down, which can happen with infection or inflammation. It is best known as a urine test, but the same enzyme can be measured in other body fluids, including serum or plasma.

: Why Might This Test Be Ordered?

: Because leukocyte esterase testing is far more established for urine and other body fluids, a serum/plasma measurement is uncommon and usually part of specialized evaluation or research. Your clinician would explain the specific reason in your case rather than relying on this test alone.

: How the Sample Is Collected

: A standard blood draw is used to obtain serum or plasma, which is then separated in the laboratory. No special preparation is typically required beyond what your care team advises for the blood draw.

: How to Interpret Results

: Results are interpreted in the context of your symptoms, other lab tests, and the fluid being tested. A single value should not be used on its own to diagnose infection or inflammation; discuss what your result means with the ordering clinician.