Skip to content

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

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

This test measures the level of creatinine, a waste product from muscle metabolism, in your blood or urine to assess kidney function.

Quick summary

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

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

Key facts at a glance

LOINC
20461-0
Short code
PZA Islt SlowMyco
Synonyms
PZA Islt SlowMyco
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
method-for-slow-growing-mycobacteria
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 healthcare provider may order this test to check for kidney problems, monitor kidney disease progression, evaluate kidney function before certain procedures, or assess how well medications are being processed by your kidneys.

What to Expect Before the Test

For blood tests, you may need to fast for 8–12 hours before the draw. For a 24-hour urine test, collect all urine over 24 hours in a special container. Hydration is usually encouraged unless advised otherwise.

How the Test Works

Blood is drawn from a vein (usually in your arm) and sent to a lab. For urine tests, you’ll provide a timed urine sample. The lab measures creatinine levels using an automated method, often enzymatic or spectrophotometric.

What the Results Mean

Higher-than-normal levels may indicate reduced kidney function, while lower levels could suggest dehydration, muscle breakdown, or liver disease. Results alone don’t diagnose kidney issues—your provider will interpret them with other factors.

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 impaired filtration, which can lead to long-term complications like fluid buildup, electrolyte imbalances, or even kidney failure if untreated. Regular monitoring helps manage chronic conditions like diabetes or hypertension.

Short name

Creatinine

Frequently asked questions

What causes creatinine levels to change?
Creatinine levels can rise due to kidney disease, dehydration, severe muscle damage, or certain medications. They may drop with overhydration, muscle loss, or liver disease. Always discuss symptoms or recent changes with your provider.
How often should I get this test?
Frequency depends on your health. Healthy adults may get baseline tests every few years. People with kidney risk factors (e.g., diabetes, high blood pressure) often need monitoring every 6–12 months.
Can diet affect creatinine levels?
Dietary protein intake can influence muscle mass, which indirectly affects creatinine production. However, standard diets don’t drastically alter lab results unless you’re in extreme conditions (e.g., very low protein intake). Always follow your provider’s advice.
  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