24-Hour Urinary Sodium Intake
This test measures how much sodium (a key mineral) you excrete in your urine over a 24-hour period. It helps assess how well your kidneys are regulating sodium balance and can identify conditions like kidney disease or excessive sodium retention.
["This test helps doctors check if your kidneys are working properly or if you’re retaining too much sodium."]
Key facts at a glance
- LOINC
- 81011-9
- Short code
- Sodium intake 24h Est
- Synonyms
- Sodium intake 24h Est
- 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
- Method
- estimated
- 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 Matters
Sodium is essential for balancing fluids, nerve function, and blood pressure. Too much sodium can strain your heart and kidneys, while too little can cause muscle cramps or irregular heartbeat. This test helps determine if your body is losing or retaining sodium appropriately.
What to Expect Before the Test
You’ll collect all your urine for a full 24-hour period (from one morning to the next). Typically, you’ll start by emptying your bladder at the beginning of the period and then collect every bit of urine for the next 24 hours. Store the urine in a cool, dark container and bring the entire sample to your doctor’s office.
How the Test Works
The collected urine is tested for sodium levels. The results are compared to a standard range to see if your sodium excretion is within normal limits or if it’s too high or too low.
Possible Causes of Abnormal Results
High sodium excretion might suggest kidney problems, excessive sweating, or certain medications. Low sodium excretion could indicate kidney disease, dehydration, or conditions like congestive heart failure. Your doctor will discuss these findings with you.
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
Short name
24h Sodium Urine
Frequently asked questions
What does a ‘normal’ result mean for me?
Can I eat or drink anything special before this test?
How long will it take to get my 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 16, 2026. · Read our editorial policy