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24-Hour Urinary Sodium and Chloride Ratio

Published: August 9, 2026Updated: August 17, 2026

This test measures the balance of sodium and chloride in your urine over 24 hours to help assess kidney function and electrolyte balance.

Quick summary

["Helps doctors check how well your kidneys filter electrolytes and detect potential imbalances."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
31107-6
Short code
OF .45% NaCl 24h Inc NFr RBC
Synonyms
OF .45% NaCl 24h Inc NFr RBC
Category
electrolyte
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
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 for Your Health

Your kidneys play a key role in regulating sodium and chloride, which are essential for fluid balance, nerve function, and blood pressure. This test helps identify if your kidneys are working properly or if there’s an imbalance that could affect your health.

What to Expect Before the Test

You’ll collect all urine for 24 hours, starting after you wake up the next morning and ending the same time the next day. Store the urine in a refrigerator and bring the entire sample to your lab. Avoid special diets unless instructed by your doctor.

How the Test Works

The test measures the ratio of sodium and chloride in your urine, which helps determine how efficiently your kidneys filter these electrolytes. This ratio can reveal kidney function, kidney disease, or conditions like hypertension.

Common Conditions This Test Helps Diagnose

This test may be used to diagnose or monitor conditions like kidney disease, hypertension, or electrolyte imbalances. It can also help assess how well your kidneys are handling fluid and mineral balance over time.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: serum

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Detecting Kidney Function and Electrolyte Imbalance

Short name

24h Na:Cl Urine Ratio

Frequently asked questions

How long does it take to get results from this test?
Results typically take 1–3 business days, depending on your lab. Your doctor will discuss the findings with you during your follow-up visit.
Can I eat or drink anything special before this test?
No special diet is needed, but avoid high-sodium foods unless your doctor advises otherwise. Drink as usual unless instructed otherwise.
What does a low or high sodium:chloride ratio mean?
A low ratio may indicate kidney problems or excessive fluid loss, while a high ratio could suggest kidney dysfunction or overhydration. Your doctor will interpret the results in the context of your overall health.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 17, 2026. · Read our editorial policy