Sodium/Creatinine Ratio, 24-Hour Urine
Measures sodium relative to creatinine in a 24-hour urine collection to help assess sodium balance, hydration, and kidney function.
["This test can help evaluate how your body handles sodium and whether recent urine levels reflect your kidney function."]
Key facts at a glance
- LOINC
- 44405-9
- Short code
- Sodium/Creat 24h Ur-sRto
- Synonyms
- Sodium/Creat 24h Ur-sRto
- 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 amount of sodium in urine collected for 24 hours and compares it with the amount of creatinine in the same collection. Creatinine is a waste product that is generally filtered by the kidneys, so the ratio helps show how much sodium is being excreted relative to kidney filtration.
Why might I need this test?
A clinician may order this test to evaluate sodium balance, investigate unusual salt loss or retention, or assess the effect of medicines such as diuretics. It may also be used alongside kidney function tests when evaluating hypertension, swelling, or symptoms related to fluid balance.
How is the test performed?
You collect all urine for a full 24-hour period, beginning after emptying your bladder at the start time and ending with the final collection at the same time the next day. The laboratory measures sodium and creatinine in the collection and calculates their ratio. The container and storage instructions should be followed exactly.
How do I prepare for the test?
Follow the collection instructions provided by your healthcare professional or laboratory. Record the start time, save every urine sample during the 24-hour period, and refrigerate the container if instructed. Do not begin or stop medicines or make major changes to your salt or fluid intake unless your clinician tells you to do so.
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 occur with increased salt intake, reduced kidney filtration, certain medicines, or conditions that cause the body to retain sodium and water. A lower ratio may occur with low salt intake, increased urinary salt loss, reduced muscle mass, or other conditions affecting kidney function and hydration. Results should be interpreted with the rest of your medical evaluation because diet, fluid intake, medicines, and collection accuracy can affect them.
Short name
24-hour urine sodium-to-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?
Can medicines affect the result?
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