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Bacterial Casts, Urine — Semiquantitative Microscopy

Published: August 9, 2026Updated: August 17, 2026

A urine microscopy test that looks for bacterial casts, which are small structures formed in the kidney tubules and may accompany infection or inflammation.

Quick summary

["Bacterial casts in urine may support a kidney-related infection or inflammatory process, but results must be interpreted with symptoms and other urine findings."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
53128-5
Short code
Bacterial casts #/area UrnS LPF
Synonyms
Bacterial casts #/area UrnS LPF
Category
liver
Sample
urine
Container
Sterile urine container
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 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 a urine sample under a microscope to look for bacterial casts. Casts are small structures that form inside the kidney tubules and are then released into the urine.

Why might I need this test?

Your clinician may order this test when you have urinary symptoms, such as painful or frequent urination, fever, flank pain, or unexplained changes in urine, especially if kidney infection is suspected.

How is the test performed?

A fresh urine specimen is examined, usually after its sediment is concentrated, and the urine is viewed under a microscope. The laboratory reports the amount of bacterial casts observed in a standardized microscopic area or field.

How do I prepare for the test?

No special preparation is usually required. If instructed, collect a clean-catch, midstream urine sample in the provided sterile container and deliver it promptly, preferably while the sample is fresh.

Reference range

Adult: 10-40 U/LN/A

Specimen: urine

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine Bacterial Casts

Frequently asked questions

Are bacterial casts the same as bacteria in the urine?
No. Bacteria are individual microorganisms, while casts are structures that form in the kidney tubules. Finding both can strengthen suspicion of a urinary or kidney infection.
Does a positive result always mean I have a kidney infection?
No. Bacterial casts can suggest kidney involvement during infection, but they may also be influenced by sample quality, contamination, or other urinary conditions. Your clinician will interpret the result in context.
Do I need to collect a special type of urine sample?
A clean-catch, midstream urine sample is generally preferred. Follow any collection instructions from your clinician or laboratory, and provide the sample promptly so cellular structures remain identifiable.
  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 17, 2026. · Read our editorial policy