Common formulas
- Cockcroft-Gault: ((140 − age) × weight) ÷ (72 × serum creatinine); multiply by 0.85 for women.
- MDRD: A four-variable equation using age, sex, race, and creatinine.
- CKD-EPI: The current standard for eGFR reporting in many labs.
Normal ranges
Creatinine clearance is generally considered normal above 90 ml/min. Mild reduction is common with aging. Values consistently below 60 ml/min may indicate chronic kidney disease.
Creatine supplement considerations
Creatine supplementation can increase serum creatinine slightly, which may make eGFR appear slightly lower. This is usually not a sign of kidney injury, but any abnormal result should be discussed with a healthcare provider.
24-hour urine collection vs blood estimate
The most accurate clearance measurement requires a 24-hour urine collection. Most clinics use blood-based eGFR because it is simpler and sufficiently accurate for screening.
Factors that affect clearance
- Age — clearance tends to decline over time.
- Muscle mass — more muscle produces more creatinine.
- Hydration — dehydration can raise creatinine temporarily.
- Medications — some drugs affect kidney filtration.
What to do with abnormal results
Do not panic if one test is slightly off. Repeat the test, review medications and supplements with your clinician, and address underlying risk factors like blood pressure or blood sugar.
Related tools & guides.
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Open the free creatine calculatorFrequently asked questions.
What is the difference between creatinine and creatine?
Creatine is a supplement and natural compound. Creatinine is its breakdown product, used as a marker of kidney function.
Can I do a creatine clearance calculation online?
Yes, many medical calculators exist, but they should not replace professional medical advice.
Should I stop creatine before blood work?
Tell your clinician you take creatine. They can decide whether to pause it before testing.
What is a dangerously low clearance?
Below 60 ml/min for three months or more suggests chronic kidney disease. Below 15 ml/min indicates kidney failure.
Can exercise affect creatinine levels?
Yes, intense exercise can temporarily raise creatinine. Rest before testing if possible.
Is eGFR the same as clearance?
eGFR is an estimate based on blood tests. True clearance can be measured with a 24-hour urine test.