Waxy Casts, Urine — Microscopy, Count per High-Power Field
Urine microscopy counts waxy casts, which are structures formed in kidney tubules and may be associated with impaired kidney function.
["Waxy casts in urine can be a sign of kidney disease, particularly reduced kidney function, but the finding must be interpreted with other test results."]
Key facts at a glance
- LOINC
- 41223-9
- Short code
- Waxy Casts #/area UrnS HPF
- Synonyms
- Waxy Casts #/area UrnS HPF
- 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-hpf
- 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 count waxy casts. These casts are made from proteins and cellular material that have molded inside the kidney's small filtering tubules.
Why might I need this test?
A clinician may order urine microscopy to evaluate kidney function, investigate suspected kidney disease, or monitor an existing kidney condition. Waxy casts are one of several types of structures that can be seen in urine sediment.
How is the test performed?
A urine sample is collected and examined under a microscope. The laboratory reports the number of waxy casts observed in standardized microscope fields, commonly expressed as casts per high-power field.
How do I prepare for the test?
Follow the collection instructions provided by the healthcare facility. A clean-catch, midstream urine sample is usually requested, and the sample should be delivered promptly and kept refrigerated if there will be a delay.
Reference range
Adult: 10-40 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.
Waxy casts may occur with longstanding or advanced reduction in kidney function, especially in chronic kidney disease. They can also appear in concentrated urine, so an isolated finding does not by itself establish a diagnosis. Results should be interpreted alongside urine protein, kidney blood tests, symptoms, and other urine microscopy findings.
Short name
Urine waxy casts
Frequently asked questions
What does a waxy cast mean?
Does this test require fasting?
Can waxy casts go away?
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