Renal Tubular Casts, Urine — Microscopy, Area
A urine microscopy test that detects and may measure renal tubular casts, structures formed in the kidney's filtering units.
["Renal tubular casts in urine can reflect kidney stress or disease, so results should be interpreted with the rest of your urinalysis."]
Key facts at a glance
- LOINC
- 30079-8
- Short code
- Renal Tub Casts #/area Ur Micro
- Synonyms
- Renal Tub Casts #/area Ur Micro
- Category
- liver
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 7
- Ref high
- 56
- Critical range
- — – 500 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- microscopy-light
- CPT
- 84484
- SNOMED
- 302773008
- 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 under a microscope to look for renal tubular casts. These small structures form inside the kidney's filtering units and may be present in the urine in certain kidney conditions.
Why might I need this test?
A clinician may order this test as part of a urinalysis to evaluate kidney function or investigate symptoms such as swelling, nausea, changes in urination, or abnormal urine color. It is often interpreted alongside other urine and blood tests.
How is the test performed?
A urine specimen is viewed under a microscope, and the laboratory checks for renal tubular casts. Depending on the laboratory's method, the result may be reported as an area, a count, or another descriptive measurement.
How do I prepare for the test?
Follow the laboratory's collection instructions. A clean-catch urine sample is usually used, and a first-morning specimen may be requested if casts are related to concentrated overnight urine.
Reference range
Adult males: 7-56 U/L; Adult females: 7-43 U/LN/A
No special preparation required. Avoid fatty meals before the test if possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Renal tubular casts can occur with dehydration or intense physical activity, particularly when the urine is concentrated. Persistent or numerous casts may be associated with kidney injury or other kidney disease, but this result alone does not establish a diagnosis.
Short name
Renal Tubular Casts, Urine
Frequently asked questions
What are renal tubular casts?
Does finding casts always mean I have kidney disease?
Will I need another test?
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