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White Blood Cell Casts, Urine — Qualitative, Computer-Assisted Microscopy

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

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

Quick summary

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

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

Key facts at a glance

LOINC
53279-6
Short code
WBC Casts Ur Ql Comp Assist
Synonyms
WBC Casts Ur Ql 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 examines a urine sample for white blood cell casts. These are small structures made of white blood cells and cellular material that form inside kidney tubules.

Why might I need this test?

Your clinician may order this test if you have symptoms of a urinary tract infection, such as painful or frequent urination, fever, or flank pain. It can also help evaluate suspected inflammation of the kidneys.

How is the test performed?

A urine specimen is analyzed using computer-assisted microscopy to look for white blood cell casts. A laboratory professional may review the results manually when needed.

How do I prepare for the test?

Follow the laboratory's collection instructions. Usually, this involves a clean-catch midstream urine sample collected after cleaning the genital area and beginning to urinate. Fasting is generally not required.

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 does a urine white blood cell cast mean?
It is a structure containing white blood cells that formed inside a kidney tubule. Its presence may support inflammation or infection involving the urinary tract or kidneys.
Does this test diagnose a kidney infection?
No. The finding can be associated with several conditions, so your clinician will interpret it along with your symptoms and other laboratory results.
Do I need to fast for this test?
Usually not. Follow any specific instructions from your healthcare provider or laboratory, particularly if this test is part of a larger urine test panel.
  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