Cockcroft-Gault formula
For men: ((140 − age) × weight in kg) ÷ (72 × serum creatinine in mg/dL). For women, multiply the result by 0.85. This gives an estimate of creatinine clearance in ml/min.
eGFR (MDRD / CKD-EPI)
Modern labs usually report estimated glomerular filtration rate (eGFR) using the CKD-EPI equation. eGFR is based on serum creatinine, age, sex, and race modifiers in some versions. Values above 90 ml/min/1.73m² are generally considered normal.
What this means for creatine users
Creatine can raise serum creatinine slightly without harming kidneys. If you are monitoring kidney function, tell your clinician that you supplement with creatine so they can interpret results correctly.
Step-by-step calculation example
For a 30-year-old man weighing 80 kg with a serum creatinine of 1.0 mg/dL: ((140 − 30) × 80) ÷ (72 × 1.0) = 122 ml/min. This falls within the normal range.
Interpreting your result
- Above 90: Normal kidney function.
- 60–89: Mild decrease, often age-related.
- Below 60: Possible chronic kidney disease; see a doctor.
When to recheck
If you are healthy, annual checkups are usually enough. If you have risk factors or take medications that affect kidneys, your clinician may recommend more frequent testing.
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Open the free creatine calculatorFrequently asked questions.
Can I calculate clearance at home?
You can estimate it if you know your serum creatinine, age, sex, and weight, but a clinician should confirm any concerns.
Does creatine lower creatinine clearance?
It does not lower true kidney function, but it can raise serum creatinine, which may make eGFR look slightly lower.
When should I see a doctor?
If your eGFR is below 60, or you have symptoms like swelling, fatigue, or changes in urination, consult a clinician before taking creatine.
What units are used for clearance?
Creatinine clearance is usually reported in milliliters per minute (ml/min).
Why do labs use eGFR instead of clearance?
eGFR is easier to measure because it only requires a blood test, while true clearance requires a 24-hour urine collection.
Does weight affect clearance calculation?
Yes. Cockcroft-Gault uses actual body weight, while eGFR is normalized to body surface area.