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White Blood Cell Casts, Urine — Microscopy, Semi-Quantitative

Published: August 9, 2026Updated: August 16, 2026

Urine microscopy that detects and estimates white blood cell casts, which can form when the kidneys are inflamed.

Quick summary

["White blood cell casts in urine may indicate inflammation or infection in the kidneys."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
33825-1
Short code
WBC Casts UrnS Ql Micro
Synonyms
WBC Casts UrnS Ql Micro
Category
liver
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
10
Ref high
40
Critical range
2 N/A – 30 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light
CPT
84484
SNOMED
302774002
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

This test examines urine under a microscope to look for white blood cell casts. These structures form in the kidney tubules when white blood cells are present in the urine.

Why might I need this test?

Urine white blood cell casts may be checked when symptoms suggest a kidney or urinary tract problem, such as painful urination, fever, flank pain, or changes in urination.

How is the test performed?

A urine sample is collected and examined microscopically. The laboratory identifies white blood cell casts and may report their presence in a semi-quantitative range rather than an exact number.

How do I prepare for the test?

Follow your clinician's collection instructions, often using a clean-catch midstream urine sample. The sample should be placed in the provided container and delivered promptly; do not stop medications unless instructed.

Reference range

Adult: 10-40 U/LN/A

Specimen: urine

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine WBC casts

Frequently asked questions

What does a positive result mean?
It means white blood cell casts were found in the urine, which can be associated with inflammation or infection involving the kidneys.
Does this test diagnose a specific condition?
No. It is one finding that clinicians combine with symptoms and other laboratory tests to determine the cause.
Can white blood cell casts be found without symptoms?
Yes. They may occasionally be present without obvious urinary symptoms, so results should be reviewed with your clinician.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy