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White Blood Cell Casts, Urine — Computer-Assisted Count

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

A urine microscopy test that detects white blood cell casts, which can form in the kidney tubules during inflammation or infection.

Quick summary

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

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

Key facts at a glance

LOINC
53286-1
Short code
WBC Casts # Ur Comp Assist
Synonyms
WBC Casts # Ur Comp Assist
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
computer-assisted
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 looks for white blood cell casts in a urine sample. These small structures form when white blood cells become trapped in material produced inside the kidney tubules.

Why might I need this test?

A clinician may order this test as part of a urinalysis when evaluating urinary symptoms, such as painful or frequent urination, fever, back pain, or changes in urine appearance. It can help assess whether inflammation or infection may involve the kidneys.

How is the test performed?

A urine specimen is examined using computer-assisted urine microscopy to identify and count white blood cell casts. A laboratory professional may also review the microscopic findings.

How do I prepare for the test?

Follow the laboratory's urine-collection instructions, which may include collecting a clean-catch midstream sample. Tell the clinician if you have a urinary tract infection, kidney disease, or recently took antibiotics.

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 white blood cell casts

Frequently asked questions

What are white blood cell casts?
They are small structures that form when white blood cells become embedded in material produced inside the kidney tubules. Their presence can be a sign of kidney inflammation.
Does a positive result always mean I have a kidney infection?
No. Although white blood cell casts can occur with a kidney infection, they may also appear with other inflammatory or noninfectious kidney conditions.
Do I need to prepare for this test?
Usually, you should collect urine as instructed by the laboratory, often using a clean-catch midstream method. Specific preparation may vary, so follow the instructions provided before collection.
  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