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Serum Creatinine (Creatinine Concentration)

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

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

Quick summary

["A creatinine test helps check kidney function and detect early kidney problems."]

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

Key facts at a glance

LOINC
56977-2
Short code
RA Nuc Ab Titr Ser IF
Synonyms
RA Nuc Ab Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
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 Is This Test Done?

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

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a larger panel. Drink plenty of water the day before to ensure accurate results.

How the Test Is Done

A small blood sample is drawn from a vein, typically in your arm. The sample is sent to a lab to measure creatinine levels.

What the Results Mean

Higher than expected levels may indicate kidney problems, while lower levels could suggest muscle breakdown or other conditions. Your doctor will interpret results in relation to your overall health.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Creatinine levels are a key marker for kidney function. Elevated levels often signal reduced kidney filtration, which can lead to serious complications like fluid buildup, electrolyte imbalances, or even kidney failure if untreated. Regular monitoring helps manage chronic kidney disease (CKD) and adjust treatments like medications or dialysis.

Short name

Creatinine

Frequently asked questions

What Causes Abnormal Creatinine Levels?
High creatinine levels may result from kidney disease, dehydration, severe muscle damage, or conditions like heart failure or liver disease. Low levels might suggest dehydration, muscle loss, or certain metabolic disorders.
How Often Should I Get This Test?
Your doctor will determine how often you need this test based on your health status. For people with kidney issues, tests may be done more frequently to track progress or adjust treatment.
Can Diet or Exercise Affect Creatinine Levels?
Dietary protein intake can influence creatinine levels, as muscle breakdown produces creatinine. However, moderate exercise is unlikely to affect results significantly. Always follow your doctor’s advice regarding diet and activity.
  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