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Nephrology Urine Flow Rate with Kidney Volume Screening (24-hour urine collection)

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

This test measures how well your kidneys filter fluids over 24 hours and evaluates kidney function through urine output and volume assessment.

Quick summary

["Assesses kidney health and fluid balance by tracking urine flow and kidney size over a full day."]

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

Key facts at a glance

LOINC
42261-8
Short code
NM Kidney Vs bld flow W RNC IV
Synonyms
NM Kidney Vs bld flow W RNC IV
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
nm
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 Is Done

Your doctor may recommend this test if you have symptoms like frequent urination, swelling, or signs of kidney issues, or if you need to monitor kidney function in chronic conditions like diabetes or hypertension.

What to Expect Before the Test

You’ll collect all urine for 24 hours in a container, starting after your first morning void. Drink normal fluids but avoid diuretics unless instructed otherwise. Return the container to your lab for analysis.

During the Test

No special preparation is needed beyond the urine collection. The test involves measuring total urine volume and analyzing urine flow rate, often combined with imaging (like ultrasound) to estimate kidney size.

What the Results Mean

Results help determine if your kidneys are filtering fluids properly, whether urine output is abnormal, and whether kidney size or function is affected by medical conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urine Flow & Kidney Volume Test

Frequently asked questions

How long does urine collection take?
Urine collection lasts 24 hours, starting after your first morning void. You’ll need to empty your bladder into a container every time, then return the full container to the lab.
What should I do if I miss a urine sample?
If you miss a sample, contact your lab or doctor immediately to adjust the collection period. Missing samples can affect test accuracy.
Can I drink alcohol during urine collection?
Avoid excessive alcohol, as it may alter urine concentration. Stick to normal fluid intake unless your doctor specifies otherwise.
  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