Serum Creatinine (Creatinine)
This test measures the level of creatinine, a waste product from muscle metabolism that your kidneys filter from the blood. It helps assess kidney function and overall kidney health.
["A creatinine test checks how well your kidneys are working."]
Key facts at a glance
- LOINC
- 41845-9
- Short code
- N men sg A+B+C+W135+Y+EcK1 Ag CSF Ql Agg
- Synonyms
- N men sg A+B+C+W135+Y+EcK1 Ag CSF Ql Agg
- Category
- chemistry
- Sample
- csf
- Container
- Sterile tube
- Units
- N/A
- Ref low
- 22
- Ref high
- 198
- Critical range
- — – 10000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- aggl
- CPT
- 82553
- Specimen volume
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters
Creatinine is a byproduct of muscle breakdown and is normally removed from your blood by your kidneys. High levels can indicate poor kidney function, while low levels may suggest overhydration or other conditions. This test is often used alongside other measures to evaluate kidney health, especially if you have symptoms like fatigue, swelling, or changes in urine output.
What to Expect Before the Test
No special preparation is needed for this test. You may have a small needle inserted into a vein in your arm to draw blood. If you’re on a diet low in meat or protein, your doctor may ask you to eat normally the day before the test.
What the Results Mean
Results are typically reported in milligrams per deciliter (mg/dL) or millimoles per liter (mmol/L). While reference ranges vary by lab, higher-than-normal levels may signal kidney problems, while very low levels might need further investigation to rule out other causes like dehydration or muscle disorders.
Common Causes of Abnormal Results
High creatinine levels can result from kidney disease, dehydration, severe muscle damage, or conditions that reduce blood flow to the kidneys. Low levels may occur with overhydration, certain medications, or conditions affecting muscle mass.
Reference range
Adult males: 22-198 U/L; Females: 22-198 U/LN/A
No special preparation required. Inform provider of any chest pain or symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Creatinine is a key marker in diagnosing and monitoring kidney disease, including chronic kidney disease (CKD) and acute kidney injury (AKI). It helps doctors track kidney function over time, especially in patients with diabetes, hypertension, or a history of kidney problems. Regular monitoring can help detect early signs of kidney damage and guide treatment decisions.
Short name
Creatinine
Frequently asked questions
What does a high creatinine level mean?
Can diet affect creatinine levels?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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