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White Blood Cell Casts, Urine

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

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

Quick summary

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

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

Key facts at a glance

LOINC
5820-6
Short code
WBC Casts #/area UrnS LPF
Synonyms
WBC Casts #/area UrnS LPF
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-lpf
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 for white blood cell casts. These are clusters of white blood cells that become molded inside the kidney tubules and are released into the urine.

Why might I need this test?

A clinician may order this test as part of a urinalysis when there are symptoms such as painful or frequent urination, fever, flank pain, or signs of kidney inflammation. It can also help evaluate suspected kidney injury or inflammatory kidney disease.

How is the test performed?

A urine sample is collected and examined in the laboratory, usually with urine sediment microscopy. The laboratory reports whether white blood cell casts are present and may describe the amount using a semi-quantitative scale or a count per microscopic field.

How do I prepare for the test?

Follow the laboratory's collection instructions, which may include a clean-catch midstream urine sample. Collect the urine at the directed time, label it properly, and deliver it promptly unless your clinician gives different instructions.

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 are white blood cell casts?
They are white blood cells that have clustered and taken the shape of kidney tubules. Their presence suggests that inflammation or infection may involve the kidneys.
Do white blood cell casts always mean I have a kidney infection?
No. They can occur with bacterial infection, but they may also appear in noninfectious inflammatory conditions, including some medication-related or autoimmune kidney disorders.
Is this the same as a routine urinalysis?
Often, white blood cell casts are evaluated as part of urine sediment microscopy during a urinalysis. Some laboratories also report the finding separately or include it in an automated urinalysis 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