Serum Creatinine (Creatinine Level)
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.
["Kidney function check: creatinine levels help detect early kidney problems."]
Key facts at a glance
- LOINC
- 111059-2
- Short code
- COLDAG
- Synonyms
- CA Msmt SerPl
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or plain red-top tube; pre-warmed to 37°C prior to collection
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Critical range
- — – 1000 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–120 years
- Method
- Agglutination assay (tube method or gel-based); serial dilution of patient serum at 4°C with type O or pooled red blood cells to detect cold-reactive antibodies (typically IgM)
- CPT
- 86157
- SNOMED
- 5471-6
- Specimen volume
- 3-5 mL of whole blood (yields approximately 1-2 mL serum); minimum 1 mL serum preferred
- Stability
- Serum kept at 37°C: 1-2 hours before separation; separated serum at 2-8°C: 24 hours; separated serum frozen at -20°C: up to 2 weeks for titer testing
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Your Kidneys Matter
Your kidneys filter waste and extra fluids from your blood to keep your body healthy. Creatinine is a byproduct of muscle activity that your kidneys remove. If your kidneys aren’t working well, creatinine levels can build up in your blood, which may indicate kidney damage or disease.
What to Expect During the Test
You’ll have a small needle inserted into your arm to draw a blood sample. This is quick and usually causes only minor discomfort. No special preparation is needed, but let your doctor or lab staff know if you’re on certain medications or have a history of bleeding disorders.
Common Causes of Abnormal Results
High creatinine levels may suggest kidney problems, but they can also be influenced by factors like dehydration, muscle damage, or certain medications. Low levels might indicate overhydration or conditions affecting muscle metabolism.
When to Ask About Results
Your doctor may order this test if you have symptoms like swelling, fatigue, or changes in urine output, or if they suspect kidney issues. Regular monitoring is also common for people with diabetes, high blood pressure, or a family history of kidney disease.
Reference range
Negative or titer <1:64 at 4°C; clinically significant cold agglutinin titers are typically ≥1:64 and often ≥1:256. Reference values may vary by laboratory and methodology.N/A
No fasting required. Specimen must be maintained at 37°C from collection until serum is separated to prevent cold agglutinin-mediated hemolysis and false-negative results. Avoid placing specimen in refrigerator prior to testing.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High creatinine levels can signal kidney dysfunction, but they’re not always a direct indicator of kidney disease. Your doctor will consider your overall health, other test results, and symptoms to interpret the meaning. Low levels may raise questions about hydration or muscle function.
Short name
Creatinine
Frequently asked questions
Why do I need this test if I don’t have kidney problems yet?
What if my creatinine level is higher than expected?
Can diet or exercise affect my creatinine levels?
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 16, 2026. · Read our editorial policy