Skip to content

Serum Creatinine (Creatinine)

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 checks kidney function by measuring waste in your blood."]

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

Key facts at a glance

LOINC
40095-2
Short code
PT 6h p chal PPP
Synonyms
PT 6h p chal PPP
Category
chemistry
Sample
plasma
Container
Lavender-top (EDTA) or Green-top (Heparin)
Units
N/A
Ref low
44
Ref high
147
Critical range
— – 5 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
coag-tissue-factor-induced
CPT
84075
SNOMED
27550007
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

Your kidneys normally filter waste products, including creatinine, from your blood. If your kidneys aren’t working well, creatinine levels can rise. This test helps doctors monitor kidney health, especially in people with conditions like diabetes, high blood pressure, or those taking certain medications that may affect kidney function.

What to Expect Before the Test

No special preparation is needed for this test. You may have a small needle inserted into your arm to draw blood. If you’re on a dialysis regimen or have had recent kidney procedures, your doctor may provide specific instructions.

What the Results Mean

Higher than expected creatinine levels may indicate reduced kidney function, while lower levels might suggest overhydration or muscle breakdown. Your doctor will interpret results in relation to your overall health and medical history.

Common Causes of Abnormal Results

Elevated creatinine can result from kidney disease, dehydration, severe muscle injury, or conditions that reduce blood flow to the kidneys. Low levels may occur with overhydration, certain medications, or liver disease.

Reference range

Adult: 44-147 U/LN/A

Specimen: plasma

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Creatinine

Frequently asked questions

Could my creatinine levels be affected by what I eat or drink?
Dietary factors like protein intake can influence creatinine levels, but they don’t change the test’s primary purpose of assessing kidney function. Hydration status is more directly tied to creatinine levels—dehydration can raise them, while overhydration may lower them.
Why do doctors order creatinine tests alongside other kidney tests?
Creatinine is often paired with tests like blood urea nitrogen (BUN) or urine tests to provide a clearer picture of kidney function. These combinations help doctors diagnose and monitor kidney disease more accurately.
Is there anything I should do if my creatinine levels are high?
If your results are high, your doctor may recommend lifestyle changes (like managing blood pressure or hydration), medications, or further testing. Always follow their guidance based on your specific situation.
  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