Skip to content

Urine Creatinine to Glomerular Filtration Rate (GFR) Ratio (24-hour collection)

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

This test measures the ratio of creatinine in your urine compared to your estimated glomerular filtration rate (GFR), a measure of how well your kidneys are filtering blood. It helps assess kidney function over a 24-hour period.

Quick summary

["This test helps evaluate kidney health and filtration efficiency by comparing urine output to kidney function."]

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

Key facts at a glance

LOINC
15289-2
Short code
Height Kidney-R US.meas
Synonyms
Height Kidney-R US.meas
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-measured
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 order this test if they suspect kidney disease, poor kidney function, or if you have conditions like diabetes or high blood pressure that can affect kidney health. It can also be used to monitor kidney function in people with chronic kidney disease or after treatment for kidney-related issues.

How the Test Works

You’ll collect all urine for a full 24-hour period in a container provided by your healthcare team. The urine is then tested for creatinine levels. Your GFR is calculated using a formula that considers your age, sex, race, and blood creatinine levels. The ratio helps determine how well your kidneys are filtering waste products from your blood.

What to Expect Before the Test

No special preparation is needed beyond collecting urine over 24 hours. Drink enough fluids to produce urine throughout the day, but avoid excessive diuretics or medications that may affect urine output unless instructed otherwise.

What to Expect During the Test

You’ll simply collect all urine in a container for 24 hours. Your healthcare team will provide clear instructions on how to properly store and handle the urine sample to ensure accuracy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

GFR:Urine Creatinine Ratio

Frequently asked questions

What does a low or high ratio mean?
A low ratio may suggest kidney disease, where your kidneys are not filtering blood properly, or conditions that reduce urine output. A high ratio could indicate dehydration, excessive fluid loss, or other factors that concentrate urine more than usual. Your doctor will interpret the results in the context of your overall health and medical history.
How often should I get this test?
The frequency depends on your health condition. If you have kidney disease or risk factors like diabetes or high blood pressure, your doctor may recommend this test more often to monitor changes in kidney function. Regular follow-ups help track progress and adjust treatments as needed.
Can I take medications before this test?
Most medications can be taken as usual unless your doctor advises otherwise. However, some medications (like certain diuretics or contrast dyes) may affect urine output or kidney function. Always inform your healthcare provider about all medications you’re taking before the test.
  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