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Serum Creatinine Clearance (Cockcroft-Gault Method)

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

This test measures how well your kidneys filter waste products from your blood, using creatinine levels and urine flow. It helps assess kidney function over time.

Quick summary

["A creatinine clearance test helps doctors check how well your kidneys are working by measuring how quickly waste products leave your blood."]

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

Key facts at a glance

LOINC
81756-9
Short code
LPT aCD3 max/CD3 NFr Bld FC
Synonyms
LPT aCD3 max/CD3 NFr Bld FC
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
0.8
Ref high
1.2
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
CPT
85610
SNOMED
396252006
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Does This Test Measure?

Creatinine is a waste product from muscle metabolism that kidneys normally filter out of your blood. This test estimates how well your kidneys are doing by tracking how quickly creatinine appears in your urine over time. The Cockcroft-Gault method combines your serum creatinine level with your urine volume and timing to calculate clearance.

Why Is This Test Important?

Kidney function declines gradually, and early detection is key. Creatinine clearance helps identify kidney problems before symptoms appear, such as fatigue, swelling, or changes in urine output.

How Is This Test Done?

You’ll provide a blood sample (serum) and a 24-hour urine collection. Blood is drawn to measure creatinine levels, while urine is collected over 24 hours to track waste excretion. The test compares these results to estimate kidney function.

What Are Common Causes of Abnormal Results?

Low clearance may signal kidney disease, dehydration, or muscle disorders. High clearance could indicate overhydration or certain kidney conditions. Other factors like diet, medications, or kidney damage can also affect results.

Reference range

INR: 0.8-1.2 (warfarin: 2.0-3.0)N/A

Specimen: whole-blood

Inform your healthcare provider if you are taking blood thinners. No special preparation required.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Clearance

Frequently asked questions

Why did my doctor order this test?
Your doctor may recommend it if you have symptoms like frequent urination, swelling, or fatigue, or if you have a history of kidney issues, diabetes, or high blood pressure. It’s also used to check kidney function before surgeries or treatments.
What should I do to prepare?
Follow your doctor’s instructions for urine collection (usually starting the night before). Avoid excessive fluid intake on the day of urine collection unless advised otherwise. On the blood draw day, eat normally but avoid strenuous activity.
Will I feel any pain or discomfort?
The blood draw is quick and may cause mild discomfort, but the urine collection involves no pain if done correctly. If you have kidney stones or urinary tract issues, let your doctor know before starting the urine collection.
  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