Sodium and Creatinine, 24-Hour Urine — Calculated Ratio
Measures sodium and creatinine in urine collected for 24 hours and may include a calculated sodium-to-creatinine ratio.
["This test estimates how much sodium is being excreted in the urine relative to creatinine."]
Key facts at a glance
- LOINC
- 56980-6
- Short code
- Sodium/Creat 24h Ur-Rto
- Synonyms
- Sodium/Creat 24h Ur-Rto
- Category
- kidney
- Sample
- urine
- Container
- Sterile urine container
- Units
- N/A
- Ref low
- 136
- Ref high
- 145
- Critical range
- 120 N/A – 160 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- CPT
- 84295
- SNOMED
- 110741000
- 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 the amounts of sodium and creatinine in urine collected over 24 hours. A sodium-to-creatinine ratio may be calculated to help show how much sodium is being lost in the urine relative to creatinine.
Why might I need this test?
A clinician may order it to assess sodium excretion, particularly when evaluating high blood pressure, kidney function, fluid balance, or the effects of medications or dietary changes.
How is the test performed?
You collect all urine for exactly 24 hours, usually in a labeled container provided by the laboratory. The laboratory measures sodium and creatinine and may calculate the sodium-to-creatinine ratio.
How do I prepare for the test?
Follow the collection instructions carefully and note the start and end times. Fasting is generally not required, but your clinician may give specific instructions about diet, salt intake, and medications; do not stop medicines without medical advice.
Reference range
Adult: 136-145 mmol/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A higher sodium-to-creatinine ratio may reflect greater sodium excretion, which can be related to sodium intake, certain medicines, kidney function, or fluid balance. A lower ratio may occur with reduced sodium intake or excretion. Results can also be affected by an incomplete urine collection, so the total amount collected and the laboratory's interpretation should be considered.
Short name
24-hour urine sodium/creatinine ratio
Frequently asked questions
Do I need to fast for this test?
What happens if I miss part of the 24-hour urine collection?
What does a high or low sodium-to-creatinine ratio mean?
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