24-Hour Urine Sodium Rate
This test measures how much sodium your body excretes in urine over a full day. Sodium is an important electrolyte that helps balance fluids and support nerve and muscle function.
["Assesses how well your kidneys are managing sodium balance over time."]
Key facts at a glance
- LOINC
- 58994-5
- Short code
- Sodium 18h Ur-sRate
- Synonyms
- Sodium 18h Ur-sRate
- Category
- electrolyte
- 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
Why This Test Matters
Your kidneys play a key role in controlling sodium levels in your body. This test helps doctors check if your kidneys are properly filtering sodium, which can be important for conditions like high blood pressure, kidney disease, or certain heart conditions.
When You Might Need It
A doctor may order this test if you have symptoms like swelling (edema), high blood pressure, or if you’re taking medications that affect sodium balance. It’s also sometimes used to monitor kidney function or evaluate fluid retention.
What to Expect Before the Test
You’ll need to collect all urine for a full 24-hour period, typically starting after midnight one day and ending the same time the next day. Drink usual fluids but avoid special diets unless instructed by your doctor.
How the Test Works
Your urine is analyzed to determine the total amount of sodium passed in that day. The result helps assess how efficiently your kidneys are managing sodium excretion.
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.
High sodium excretion may indicate overactive kidneys or certain kidney disorders, while low excretion could suggest kidney dysfunction, hormonal imbalances, or medications affecting sodium retention. This test helps diagnose and monitor conditions like hypertension, kidney disease, or syndrome of inappropriate antidiuretic hormone (SIADH).
Short name
24-Hour Sodium Excretion Rate
Frequently asked questions
What does a high sodium excretion rate mean?
What does a low sodium excretion rate mean?
How often should I get this test?
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