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White Blood Cell Casts per Microscopic Area, Urine

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

Urine microscopy looks for white blood cell casts, which form in the kidney tubules and may indicate inflammation or infection.

Quick summary

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

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

Key facts at a glance

LOINC
88976-6
Short code
WBC Casts #/area UrnS
Synonyms
WBC Casts #/area UrnS
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
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 urine microscopy test identifies and counts white blood cell casts per microscopic area. These casts are cylindrical structures made of white blood cells that form inside kidney tubules.

Why might I need this test?

A clinician may order this test as part of a urinalysis, particularly if you have urinary symptoms, fever, flank pain, or kidney function concerns. It can help evaluate whether inflammation or infection may involve the kidneys.

How is the test performed?

A urine sample is examined under a microscope, and any white blood cell casts are counted relative to the microscopic field area. Results may be reported alongside other urine microscopy findings.

How do I prepare for the test?

Follow your clinician or laboratory's collection instructions, which may call for a clean-catch, midstream urine sample. Fresh urine in a sterile container is usually preferred, and 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 are white blood cell casts?
They are small, tube-shaped structures containing white blood cells that form in the kidney tubules. Finding them in urine points to a process involving the kidneys.
Do white blood cell casts always mean I have an infection?
No. Infection is one possible cause, but kidney inflammation and some other conditions can also produce them. The result must be interpreted with the rest of your evaluation.
Is this the same as a urine white blood cell count?
No. A urine white blood cell count measures individual cells, while this test identifies and counts white blood cell casts. Both may be included in a complete urinalysis.
  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