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Urine Urinary Sodium Concentration (24-Hour Collection)

Published: August 9, 2026Updated: August 16, 2026

This test measures the total amount of sodium (a key electrolyte) in your urine over a full day. It helps assess how well your kidneys are balancing sodium levels in your body.

Quick summary

["Understanding your sodium balance can help identify kidney function or fluid/ electrolyte disorders."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
25315-3
Short code
11DC 24h Ur-sRate
Synonyms
11DC 24h Ur-sRate
Category
hormone
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 Is Done

Your doctor may order this test if they suspect conditions like kidney disease, high blood pressure, or certain hormonal imbalances that affect sodium retention or excretion. It can also help evaluate how well you’re managing medications that affect sodium levels, such as diuretics.

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 just after midnight the next. Drink plenty of fluids to help your urine flow normally, but avoid foods high in sodium (like processed snacks) unless instructed otherwise.

How the Test Is Done

You’ll provide a 24-hour urine sample in a special container. The lab will analyze the sample to measure sodium concentration, often combined with other urine tests for comprehensive evaluation.

What the Results Mean

Results are usually reported as the total sodium amount excreted in urine (in milligrams or milliequivalents) over 24 hours. Abnormal results may indicate over- or underexcretion of sodium, which can signal kidney issues, fluid imbalances, or other health concerns.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormally high sodium excretion (hypernatriuria) may suggest conditions like kidney disease, excessive sweating, or certain medications. Low sodium excretion (hyponatriuria) could indicate kidney dysfunction, hormonal disorders (e.g., adrenal insufficiency), or poor kidney filtering. Monitoring sodium balance helps guide treatment for hypertension, heart failure, or electrolyte disorders.

Short name

24-Hour Urine Sodium

Frequently asked questions

How long does a 24-hour urine collection take?
A 24-hour urine collection requires you to collect all urine for a full day, which can feel time-consuming. You’ll need to empty your bladder at the start and end of the period, and store the sample in a refrigerator to keep it fresh. Most patients find it helpful to set reminders or use a timer to track progress.
Can I eat or drink anything during the 24-hour urine collection?
Yes, but avoid excessive sodium intake unless your doctor specifies otherwise. Drink plenty of water to help your urine flow naturally, but skip highly salty foods like processed snacks, deli meats, or canned soups unless instructed to do so.
What if I miss any urine during the collection period?
If you miss urine, you’ll need to restart the collection from the beginning. Small amounts missed may not significantly affect results, but missing a large portion could lead to inaccurate readings. Always follow your doctor’s instructions precisely.
  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 16, 2026. · Read our editorial policy