The primary screening test for detecting white blood cells (WBCs) in urine is the leukocyte esterase test. This test identifies a substance indicating the presence of white blood cells, which often suggests a possible urinary tract infection (UTI).
Understanding the Leukocyte Esterase Test
- How it works: The leukocyte esterase test detects an enzyme (leukocyte esterase) produced by white blood cells. If this enzyme is present in the urine, it indicates that WBCs are likely present.
- What a positive result means: A positive result on the leukocyte esterase test suggests a possible UTI.
- Follow-up test: When the leukocyte esterase test is positive, the urine should be examined under a microscope to confirm the presence of WBCs and to look for other indicators of infection, such as bacteria.
Microscopic Examination of Urine
If the leukocyte esterase test is positive, a microscopic exam is necessary. This confirms the presence of WBCs and helps determine if other elements, such as:
- Bacteria
- Red blood cells
- Casts
Are also present, assisting in the diagnosis of the cause of the infection.
Summary of WBC Testing in Urine
| Test | What it detects | Purpose |
|---|---|---|
| Leukocyte Esterase Test | Enzyme from WBCs | Initial screening for WBCs, suggesting a possible infection. |
| Microscopic Examination | Actual WBCs, bacteria, red blood cells, casts | Confirms WBC presence and identifies other infection-related elements. |
Practical Insight
- It's important to note that a positive leukocyte esterase test doesn't always mean a UTI is present. Other factors might lead to a positive result. Therefore, further microscopic examination and clinical assessment are crucial for accurate diagnosis.
- The presence of WBCs in urine indicates inflammation, typically as a reaction to a UTI or other conditions.
