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Creatinine Clearance (24-hour urine collection)

Published: August 9, 2026Updated: August 15, 2026

This test measures how well your kidneys filter waste products from your blood over a 24-hour period, using a urine sample.

Quick summary

["Assesses kidney function by tracking how efficiently your kidneys remove creatinine from your blood."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
59241-0
Short code
CGA
Synonyms
CgA Fld-aCnc
Category
chemistry
Sample
serum
Container
Red-top serum tube (no anticoagulant) or serum separator tube (SST)
Units
N/A
Ref low
0
Ref high
93
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Enzyme-Linked Immunosorbent Assay (ELISA)
CPT
83519
SNOMED
104976003
Specimen volume
1-2 mL of serum
Stability
Room temperature: 8 hours; Refrigerated (2-8°C): 48 hours; Frozen (-20°C or below): 3 months. Avoid repeated freeze-thaw cycles.
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
24–96 hours
Order
routine

Why This Test Is Done

Your doctor may order this test to evaluate kidney health, especially if you have symptoms like fatigue, swelling, or changes in urine output. It’s also used to monitor kidney function in people with diabetes, high blood pressure, or other conditions that affect kidney function.

What to Expect Before the Test

You’ll collect all your urine for a full 24 hours, starting after you wake up the next morning and ending just before you wake up the following day. Store the urine in a refrigerator and bring the total volume to your lab visit. Avoid using diuretics or certain medications that could affect results.

During the Test

No special preparation is needed during the test itself, but you’ll need to accurately measure and record every drop of urine. A lab technician will analyze the urine sample for creatinine levels and calculate clearance based on your urine volume and blood creatinine levels.

What the Results Mean

Results are typically reported as a clearance rate (e.g., milliliters per minute or milliliters per hour). Lower than expected values may indicate kidney damage or disease, while higher values could suggest overhydration or other conditions.

Reference range

Reference range not established for body fluid; serum reference range: <93 ng/mL (varies by assay manufacturer). Results from body fluid should be interpreted in conjunction with clinical findings and compared to serum levels.N/A

Specimen: serum

No special patient preparation required. Fasting is not necessary prior to specimen collection. However, proton pump inhibitors (PPIs) and H2 receptor antagonists should be discontinued at least 2 weeks prior to testing as they can significantly elevate Chromogranin A levels.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine clearance is a gold-standard measure for assessing kidney function because creatinine is a waste product naturally produced by muscle metabolism and filtered by the kidneys. Abnormal results can signal early kidney problems, guide treatment decisions, or help monitor chronic kidney disease progression.

Short name

24-Hour Creatinine Clearance

Frequently asked questions

How is creatinine clearance different from a simple blood creatinine test?
Creatinine clearance measures how well your kidneys filter creatinine from urine over 24 hours, giving a more comprehensive picture of kidney function than a single blood test. A blood test only measures creatinine levels in your blood, while clearance accounts for urine output and volume.
What causes low creatinine clearance?
Low creatinine clearance can result from kidney disease, dehydration, severe infections, or conditions like diabetes or high blood pressure that damage kidney function. It may also occur in people with muscle disorders or those taking certain medications that affect kidney function.
How often should I get this test?
Your doctor will determine how often you need this test based on your health status. People with kidney disease or risk factors (like diabetes or hypertension) may need it more frequently, while others with stable kidney function may only need it occasionally.
  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 15, 2026. · Read our editorial policy