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24-Hour Urine Volume (Kidney Function)

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

This test measures the total amount of urine produced over a 24-hour period to assess kidney function and hydration status.

Quick summary

["Understanding your urine output helps doctors check if your kidneys are working properly and if you’re drinking enough fluids."]

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

Key facts at a glance

LOINC
15318-9
Short code
Volume Kidney-R by AUT
Synonyms
Volume Kidney-R by AUT
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-derived-aut
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

Your kidneys filter waste and excess fluids from your blood, forming urine. Measuring urine volume helps determine if your kidneys are efficiently removing waste or if fluid balance is disrupted. Low or high urine volumes may signal dehydration, kidney disease, or other health concerns.

What to Expect Before the Test

You’ll typically collect all urine produced in a 24-hour period in a special container. Drink fluids as usual unless instructed otherwise. Avoid diuretics (like caffeine or certain medications) unless approved by your doctor.

What the Results Mean

A normal urine volume varies by age, sex, and activity level. Very low volumes may indicate dehydration, kidney issues, or restricted fluid intake, while unusually high volumes could suggest overhydration, diabetes insipidus, or kidney dysfunction.

Common Causes of Abnormal Results

Low urine output might be due to dehydration, kidney problems, heart failure, or certain medications. High urine output could result from diabetes, kidney disease, or excessive fluid intake. Always discuss results with your healthcare provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

None

Frequently asked questions

How often do I need this test?
This test is often ordered if you have symptoms like frequent urination, fatigue, swelling, or if your doctor suspects kidney issues. It may also be part of routine check-ups for certain conditions (e.g., diabetes, heart disease). Your doctor will determine if repeat testing is needed.
What should I do if my urine volume is very low?
If your urine volume is significantly low, drink more fluids (unless advised against it by your doctor) and contact your healthcare provider immediately. They may recommend further tests or adjustments to your treatment plan.
Can diet affect this test?
Yes, certain foods (like salt or caffeine) can influence urine volume. Avoid excessive salt or caffeine 24 hours before testing unless directed otherwise, as they may alter results.
  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