Creatinine Clearance (Serum-Based)Medically reviewed by WellAlly Editorial Team·Last reviewed August 16, 2026·[Editorial policy](https://wellally.tech/editorial-policy)
## Key facts at a glance
LOINC45192-2Short codeCARNRATSynonymsCarn esters/C0 DBS-sRtoCategorychemistrySampleserumContainerDried Blood Spot (DBS) collection card - Whatman 903 filter paper or equivalentUnitsN/ARef low0Ref high0.4Critical range— – 0.4 N/AFastingfalsePopulationadultSexallAge range0–999 yearsMethodTandem Mass Spectrometry (MS/MS)CPT82017SNOMED4461006Specimen volumeMinimum 3-5 blood spots (each spot ~75-100 µL of whole blood) on filter paper cardStabilityDBS cards are stable for up to 14 days at room temperature, 30 days at 2-8°C, and longer at -20°C. Avoid exposure to direct sunlight, heat, and humidity.Hemolysis max500Lipemia max1000Icterus max500TAT24–72 hoursOrderroutine
## What Is Creatinine Clearance?


Creatinine clearance is a measure of kidney function that estimates how well your kidneys filter waste products like creatinine from your blood. Unlike a single blood test, this test combines your blood creatinine level with a urine sample to calculate how much waste your kidneys remove over time. It helps doctors assess how well your kidneys are working to keep your body healthy.


## How Is the Test Done?


For this test, 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 measure how much creatinine is excreted. Some clinics may use a simplified 24-hour urine method or a single urine sample with a timed collection, but the full 24-hour method provides the most accurate result.


## Why Is This Test Important?


Creatinine clearance helps doctors diagnose and monitor kidney disease, track how well treatments are working, and identify early signs of kidney problems. It’s particularly useful for people with diabetes, high blood pressure, or other conditions that may affect kidney function.


## What Does the Result Mean?


Results are typically reported in milliliters per minute (mL/min) or milliliters per hour (mL/hr). Lower values may indicate kidney damage or reduced function, while higher values could suggest overhydration or other conditions. Your doctor will interpret the result in relation to your overall health and medical history.


Reference range


Carnitine ester/free carnitine (C0) molar ratio: 0.00-0.40 (newborn/pediatric DBS screening values may vary by laboratory)N/A

Specimen: serum

No special preparation required. For newborn screening, sample is typically collected via heel stick 24-48 hours after birth.


## Clinical interpretation


How abnormal results are interpreted and what conditions they suggest.


Clinical Significance: Kidney Function Assessment


## Short name


Creatinine Clearance


## Frequently asked questions
How often will I need this test?The frequency depends on your health condition. People with kidney disease or risk factors (like diabetes or high blood pressure) may need this test more often, while healthy individuals may only need it occasionally. Your doctor will determine the best schedule for you.What if my results are abnormal?If your results are abnormal, your doctor may recommend further testing, adjustments to medications, or lifestyle changes to support kidney health. They’ll work with you to understand the cause and develop a plan to manage it.Can I eat or drink anything before the test?For the blood draw, you can eat and drink normally. For the 24-hour urine collection, follow your doctor’s instructions carefully—typically, you’ll collect all urine for 24 hours, including at night, and discard your first morning urine on the day of collection.
## Sources
3
1. 1MedlinePlus — Laboratory TestsSource
2. 2Lab Tests OnlineSource
3. 3Mayo 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