Retinol-Binding Protein/Creatinine Ratio, 24-Hour Urine
A 24-hour urine test that measures retinol-binding protein relative to creatinine to help evaluate how well the kidneys’ small tubes reabsorb filtered protein.
["A low urine RBP-to-creatinine ratio can suggest reduced function of the kidney’s filtering tubules."]
Key facts at a glance
- LOINC
- 96400-7
- Short code
- Retinol Bind Prot/Creat 24h Ur
- Synonyms
- Retinol Bind Prot/Creat 24h Ur
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 38
- Ref high
- 98
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- 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?
Retinol-binding protein is a small protein that is normally filtered by the kidneys and then reabsorbed by the kidney tubules. This test measures its amount in urine relative to creatinine, which helps account for differences in urine concentration.
Why might I need this test?
Your clinician may order this test to assess kidney tubule function, particularly if you have kidney disease, excess protein in the urine, or signs of impaired nutrient or protein handling by the kidneys.
How is the test performed?
You collect all urine produced over a 24-hour period. The laboratory measures retinol-binding protein and creatinine in the collection and calculates their ratio.
How do I prepare for the test?
Follow the collection instructions provided by the laboratory, including the exact start and stop times. Keep the container refrigerated if instructed, record any urine lost or missed, and return the collection promptly.
Reference range
NCBI: Vitamin A 38-98 µg/dLN/A
No special preparation usually required. Stay well hydrated. Inform your healthcare provider of all medications and supplements you are taking.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A lower-than-expected retinol-binding protein-to-creatinine ratio may indicate that the kidney tubules are not adequately reabsorbing filtered protein. Results should be interpreted with urine protein measurements, kidney function tests, your symptoms, and other clinical findings because dehydration and other conditions can also affect urine measurements.
Short name
24-Hour Urine RBP/Creatinine Ratio
Frequently asked questions
What does the retinol-binding protein-to-creatinine ratio show?
Why is a 24-hour urine collection used?
Does this test require fasting?
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