Red Blood Cell Casts, Urine Sediment — Computer-Assisted Microscopy
This urine test looks for red blood cell casts, which can indicate bleeding or inflammation within the kidneys.
["Red blood cell casts in urine may suggest kidney inflammation, especially when blood or protein are also present."]
Key facts at a glance
- LOINC
- 107173-7
- Short code
- RBC Casts # UrnS Comp Assist
- Synonyms
- RBC Casts # UrnS Comp Assist
- Category
- liver
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 10
- Ref high
- 40
- Critical range
- 2 N/A – 7 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 urine sediment for red blood cell casts. Casts are structures formed inside kidney tubules and are viewed with microscopy; computer-assisted analysis may be used to help identify them.
Why might I need this test?
Your clinician may order this test if you have blood in the urine, protein in the urine, reduced urine output, swelling, or other symptoms that could suggest a kidney condition.
How is the test performed?
A urine sample is collected and prepared for microscopic examination. The laboratory uses computer-assisted analysis or another microscopy method to look for red blood cell casts, and findings may be confirmed by a laboratory professional.
How do I prepare for the test?
Collect urine in the container provided by the laboratory, usually using a clean-catch midstream technique. Follow any instructions from your clinician, particularly if the test is timed or part of a broader urinalysis.
Reference range
Adult: 10-40 U/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Red blood cell casts can occur when red blood cells become trapped in proteins formed within the kidney tubules. Their presence may support inflammation or bleeding in the kidneys, including some forms of glomerulonephritis, particularly when urine also contains blood or protein. An isolated finding should be interpreted by your clinician alongside symptoms and other urine and blood test results.
Short name
Urine red blood cell casts
Frequently asked questions
What does a red blood cell cast mean?
Is this the same as blood in the urine?
Does an abnormal result always mean I have kidney disease?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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