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Serum or Plasma Creatinine Concentration (Qualitative or Quantitative)

Published: August 9, 2026Updated: August 17, 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

["Kidney function check: creatinine levels help detect early kidney problems."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
2320-0
Short code
GGCS RBC-cCnc
Synonyms
GGCS RBC-cCnc
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Your Kidneys Matter

Your kidneys filter waste products, including creatinine, from your blood. High levels may signal kidney issues, while low levels could indicate dehydration or muscle breakdown. This test is often used alongside other measures like blood urea nitrogen (BUN) to evaluate kidney health.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours before testing if your doctor specifies it. Drink plenty of water the day before to ensure accurate results.

Common Causes of Abnormal Results

Elevated creatinine levels may suggest kidney disease, dehydration, or conditions like heart failure or severe muscle damage. Lower levels might indicate dehydration, overhydration, or muscle loss. Always discuss results with your healthcare provider.

When This Test Might Be Ordered

Your doctor may order this test if you have symptoms like fatigue, swelling, frequent urination, or if you’re at higher risk for kidney problems (e.g., diabetes, high blood pressure, or a family history of kidney disease).

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: whole-blood

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine Level (Serum/Plasma)

Frequently asked questions

Why might my creatinine level be higher than expected?
Possible reasons include kidney disease, dehydration, severe muscle injury, or conditions like heart failure. Your doctor will review your full medical history and other test results to determine the cause.
Could food or medications affect my creatinine test?
Some medications (like NSAIDs or certain diuretics) or foods high in protein may influence results. If your doctor gave specific instructions, follow them closely to avoid confusion.
Is a creatinine test painful or uncomfortable?
No, it’s a simple blood draw—like a typical lab test. You may feel a slight pinch, but it’s over quickly. Most people don’t experience discomfort afterward.
  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 17, 2026. · Read our editorial policy