Phosphate and Creatinine, 24-Hour Urine
Measures phosphate and creatinine in urine collected over 24 hours to assess mineral excretion and help evaluate kidney and bone-related conditions.
["This test estimates how much phosphate your body loses in urine and uses the collection period to improve interpretation."]
Key facts at a glance
- LOINC
- 13795-0
- Short code
- Phosphate/Creat 24h Ur
- Synonyms
- Phosphate/Creat 24h Ur
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 2.5
- Ref high
- 4.5
- Critical range
- 1 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84100
- 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 measures phosphate and creatinine in all urine collected for 24 hours. Phosphate is a mineral important for bones, energy metabolism, and cell function, while creatinine is a waste product made by the muscles.
Why might I need this test?
A clinician may order it to investigate unusual phosphate loss, kidney stone risk, bone or calcium disorders, or changes in kidney function. Results may also help monitor certain medicines or conditions that affect phosphate and calcium balance.
How is the test performed?
You collect all urine for a full 24-hour period in a labeled container provided by the laboratory. The laboratory measures the amount of phosphate and creatinine in the collection, and the results may be interpreted together to account for the amount of urine produced.
How do I prepare for the test?
Follow the laboratory's collection instructions exactly, including the start and end times. Continue your usual diet and medicines unless your clinician tells you otherwise, and ask the laboratory how to store the container and what to do if any urine is missed.
Reference range
Adult: 2.5-4.5 mg/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.
High urinary phosphate can occur with kidney dysfunction, high blood phosphate, reduced parathyroid hormone activity, or certain medicines. Low urinary phosphate can occur when blood phosphate is low, parathyroid hormone is elevated, phosphate is being retained by the kidneys, or intake is reduced. Interpretation depends on blood tests, kidney function, diet, medicines, and the completeness of the urine collection.
Short name
24-Hour Urine Phosphate and Creatinine
Frequently asked questions
Why is a 24-hour urine collection used?
Does this test require fasting?
What can affect the results?
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