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Serum Creatinine (with optional 24-hour urine collection for creatinine clearance calculation)

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

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or urine. It helps assess how well your kidneys are filtering blood.

Quick summary

["Kidney function and filtering efficiency are evaluated with this test."]

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

Key facts at a glance

LOINC
36035-4
Short code
MR Kidney-L
Synonyms
MR Kidney-L
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
mr
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

Why This Test Matters

Creatinine levels can indicate kidney function and help detect early kidney damage. High levels may suggest reduced kidney function or kidney disease, while low levels could indicate overhydration or other conditions.

What to Expect Before the Test

No special preparation is needed for a blood test. For a 24-hour urine test, collect all urine over 24 hours in a container, keeping it refrigerated. Drink usual fluids unless instructed otherwise.

Common Causes of Abnormal Results

Elevated creatinine may result from kidney disease, dehydration, muscle breakdown, or conditions like heart failure. Low creatinine could indicate dehydration, overhydration, or muscle loss. Other factors like diet or medications may also affect results.

When You Might Need This Test

Doctors order this test to monitor kidney health, diagnose kidney disease, check for dehydration, evaluate chronic conditions like diabetes or heart disease, or assess potential kidney damage from medications or toxins.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level

Frequently asked questions

Could my creatinine level be affected by what I eat or drink?
Dietary protein intake can influence creatinine levels, but results are typically interpreted in relation to your body size and overall health. Hydration status also plays a role—dehydration can raise creatinine levels.
What if my test results are out of the normal range?
Your doctor will discuss the meaning of your results in the context of your medical history, symptoms, and other tests. They may recommend follow-up tests or treatments to address any concerns.
How often should I get this test?
Frequency depends on your health status. Regular monitoring may be needed if you have kidney disease, diabetes, or other conditions affecting kidney function. Your doctor will guide you on timing.
  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