Free Hydroxyproline-to-Creatinine Ratio, 24-Hour Urine
Measures urine hydroxyproline relative to creatinine over 24 hours. It can help assess collagen breakdown and may be used in the evaluation of bone and connective-tissue disorders.
["This test estimates collagen breakdown by measuring hydroxyproline relative to creatinine in a 24-hour urine collection."]
Key facts at a glance
- LOINC
- 56686-9
- Short code
- OH-Proline Free/Creat 24h Ur-Rto
- Synonyms
- OH-Proline Free/Creat 24h Ur-Rto
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- 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?
Hydroxyproline is released when collagen, the body's main structural protein, breaks down. This test measures urinary hydroxyproline compared with creatinine in urine collected for 24 hours, which helps account for differences in urine concentration.
Why might I need this test?
A clinician may order this test to evaluate increased collagen breakdown in people with suspected bone disease, vitamin D-related problems, or certain connective-tissue conditions. It may also be used alongside bone-density testing and other laboratory studies.
How is the test performed?
You collect all urine for a full 24-hour period, usually in a labeled container provided by the laboratory. The laboratory measures hydroxyproline and creatinine and calculates their ratio.
How do I prepare for the test?
Follow the laboratory's collection instructions carefully, including the start and end times. Inform your clinician about vitamin or collagen supplements, because they can affect results; do not change your diet or supplements unless instructed.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
An elevated hydroxyproline-to-creatinine ratio may indicate increased collagen breakdown, which can occur with some bone disorders, healing after fractures, or certain connective-tissue diseases. Results should be interpreted with symptoms, medical history, bone-density findings, and other laboratory tests because diet, supplements, and urine collection quality can also affect them.
Short name
24-Hour Urine Hydroxyproline/Creatinine Ratio
Frequently asked questions
Does this test measure how much calcium is in my bones?
Why is a 24-hour urine collection required?
What if I miss part of the urine collection?
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 16, 2026. · Read our editorial policy