Creatinine
Everything you need to know about Creatinine levels, including what normal ranges look like and what abnormal results might indicate.
Standard Reference Range
Unit: mg/dLReference ranges may vary slightly between laboratories. Always consult your doctor for interpretation.
What is Creatinine?
Creatinine is a waste product from muscle metabolism that's filtered by the kidneys. It's one of the best markers of kidney function.
Key Takeaway
Creatinine levels reflect kidney filtering ability. Higher levels indicate reduced kidney function.
Why is this test performed?
Creatinine is measured to:
- Assess kidney function
- Monitor chronic kidney disease
- Adjust medication dosages
- Calculate eGFR (estimated filtration rate)
- Screen for kidney damage
Interpreting Your Results
High Levels (Elevated Creatinine)
Kidney Related:
- Acute kidney injury
- Chronic kidney disease
- Kidney obstruction
- Dehydration
- Reduced blood flow to kidneys
Other Factors:
- High muscle mass (bodybuilders)
- Recent high protein meal
- Certain medications
- Rhabdomyolysis (muscle breakdown)
Low Levels
Rarely clinically significant:
- Low muscle mass
- Malnutrition
- Liver disease
- Pregnancy
Understanding eGFR
Your creatinine is used to calculate eGFR (estimated Glomerular Filtration Rate):
- ＞90: Normal kidney function
- 60-89: Mild reduction
- 30-59: Moderate reduction (Stage 3 CKD)
- 15-29: Severe reduction (Stage 4 CKD)
- ＜15: Kidney failure (Stage 5 CKD)
Important Notes
Creatinine can lag behind actual kidney function. A doubling of creatinine means kidney function has dropped by 50%.
Related Tests
- BUN: Another kidney function marker
- eGFR: Calculated from creatinine
- Urine creatinine: For clearance calculation
- Cystatin C: Alternative kidney marker
Decode your Serum Creatinine Results
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