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Serum Creatinine with Renal Function Index (Creatinine Clearance Rate)

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

This test measures how well your kidneys filter waste products from your blood, using creatinine as a marker. It helps assess kidney function and how effectively your kidneys are removing waste.

Quick summary

["A creatinine clearance test helps doctors check if your kidneys are working properly and identify early signs of kidney problems."]

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

Key facts at a glance

LOINC
30747-0
Short code
XR port Ribs Views
Synonyms
XR port Ribs Views
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-portable
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 Does This Test Measure?

Creatinine is a waste product naturally produced in your body from muscle metabolism. Your kidneys filter this waste from your blood. This test estimates how much creatinine your kidneys remove from your blood over time, which reflects their filtering ability.

Why Is This Test Done?

Doctors may order this test if you have symptoms of kidney disease (such as swelling, fatigue, or frequent urination), if you have a condition that affects kidney function (like diabetes or high blood pressure), or as part of routine check-ups for high-risk individuals.

How Is This Test Performed?

A blood sample is taken from a vein in your arm. The sample is sent to a lab where creatinine levels are measured, and your creatinine clearance rate is calculated based on your urine volume and creatinine levels over a set time (often 24 hours).

What Are Common Results?

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

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Clearance

Frequently asked questions

What Does a Low or High Clearance Mean?
A low creatinine clearance suggests your kidneys are not filtering waste efficiently, which may mean they are damaged or not working well. This could be due to kidney disease, diabetes, high blood pressure, or other conditions. A high clearance might suggest you’re drinking too much fluid or have a temporary issue with kidney function.
How Often Should I Get This Test?
Your doctor will determine how often you need this test based on your health. If you have kidney-related conditions, tests may be done more frequently to monitor progress. Follow-up recommendations are personalized.
Can I Eat or Drink Anything Before the Test?
For a 24-hour urine collection, you’ll need to collect all urine over 24 hours, starting after your first morning urine. For blood tests, you can eat and drink normally unless instructed otherwise. Proper collection is critical for accurate results.
  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