24-Hour Sodium Urine Collection (Total Sodium)
This test measures the total amount of sodium (a key electrolyte) excreted in your urine over a full 24-hour period.
["Understanding your sodium balance helps assess kidney function and fluid balance."]
Key facts at a glance
- LOINC
- 2957-9
- Short code
- Sodium Cl 24h Ur+SerPl-vRate
- Synonyms
- Sodium Cl 24h Ur+SerPl-vRate
- Category
- electrolyte
- Sample
- serum
- Container
- Red-top tube (SST)
- 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
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test if they suspect conditions like kidney disease, excessive sweating, or improper fluid balance that could affect how your body regulates sodium. It can also help diagnose or monitor conditions like hyponatremia (low sodium) or hypernatremia (high sodium).
What to Expect Before the Test
You’ll need to collect all urine for 24 hours, starting from one point in time (often midnight or midnight the next day). Drink enough fluids to produce about 600–800 mL (2–3 cups) of urine per day. Empty your bladder before starting the collection, then keep all urine in a sealed container until the test is complete.
What Happens During the Test
No special procedure is needed. The collected urine sample is sent to a lab for analysis. The lab measures the total sodium content in your urine to determine how much your body is excreting over 24 hours.
What the Results Mean
Results help doctors evaluate how well your kidneys are removing sodium. Abnormal results may indicate issues with fluid balance, kidney function, or conditions affecting electrolyte levels.
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.
◆Associated findings1
Frequently asked questions
How much sodium is excreted in urine can reveal problems like kidney disease, excessive sweating, or hormonal imbalances that affect sodium retention. For example, low sodium excretion might suggest kidney failure or improper hormone function, while high levels could indicate dehydration or certain metabolic disorders.
Your doctor may ask you to follow specific instructions, such as limiting certain foods or medications, to ensure accurate results. Always confirm these with your healthcare provider before starting the collection.
If you have kidney disease, diabetes, or other conditions that affect fluid balance, this test may be especially important to monitor sodium levels and prevent complications.
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