Skip to content

Urine Creatinine-to-Creatinine Clearance Ratio (or related functional assessment of renal function)

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

This test evaluates how well your kidneys filter waste products from your blood by measuring creatinine levels in urine and estimating kidney function through clearance calculations.

Quick summary

["Helps assess kidney health by comparing urine and blood creatinine levels to estimate how efficiently your kidneys remove waste."]

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

Key facts at a glance

LOINC
25021-7
Short code
Deprecated Bladder+Urethra Flr W vdg
Synonyms
Deprecated Bladder+Urethra Flr W vdg
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-fluor
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

What This Test Measures

Creatinine is a waste product naturally produced by your muscles as they break down energy. Healthy kidneys filter this waste into urine. This test estimates how effectively your kidneys clear creatinine from your blood by comparing urine creatinine levels to blood creatinine levels.

Why It’s Done

Doctors may order this test to check for kidney disease, monitor chronic kidney conditions, or evaluate kidney function before certain procedures. It’s also used to assess how well dialysis is working.

Sample Collection Process

You’ll likely collect a 24-hour urine sample, which means collecting all urine for a full day. Your healthcare provider will give you instructions to ensure accuracy. Blood may also be drawn to measure baseline creatinine levels.

What to Expect After the Test

No special follow-up is needed unless your doctor requests additional tests or monitoring. Results may take a few days to process, depending on lab procedures.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Urine Creatinine Clearance (Functional Kidney Test)

Frequently asked questions

What does a low or high result mean?
Low clearance may indicate impaired kidney function, while abnormally high values could suggest overhydration, dehydration, or other metabolic issues. Always discuss results with your doctor, as they’ll consider your overall health and medical history.
How often should I get this test?
Your doctor will determine the frequency based on your health condition. For example, people with kidney disease may need regular monitoring, while others may only need it occasionally.
Can I eat or drink anything before this test?
For a 24-hour urine sample, follow your doctor’s instructions carefully—typically, you’ll avoid certain medications or foods that might affect results. Blood draws may require fasting, so check with your provider beforehand.
  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