Creatinine Clearance Calculator

Calculate creatinine clearance using the Cockcroft-Gault equation to estimate kidney function and guide medication dosing.

Cockcroft-Gault Equation: CrCl (mL/min) = [(140 - Age) � Weight (kg)] / [72 � Serum Creatinine (mg/dL)] For Females: Multiply result by 0.85 Where: � Age = Patient age in years � Weight = Body weight in kilograms � Serum Creatinine = mg/dL � 72 = Constant factor � 0.85 = Female correction factor CKD Stages (by CrCl): � Stage 1: = 90 mL/min (Normal or high) � Stage 2: 60-89 mL/min (Mildly decreased) � Stage 3: 30-59 mL/min (Moderately decreased) � Stage 4: 15-29 mL/min (Severely decreased) � Stage 5: < 15 mL/min (Kidney failure)
Example: Elderly male patient for medication dosing Age: 70 years Weight: 75 kg Gender: Male Serum Creatinine: 1.2 mg/dL Calculation: CrCl = [(140 - 70) � 75] / [72 � 1.2] CrCl = [70 � 75] / 86.4 CrCl = 5,250 / 86.4 CrCl = 60.8 mL/min Results: � Creatinine Clearance: 60.8 mL/min � CKD Stage: Stage 2 (mildly decreased) � Interpretation: Mildly decreased kidney function Clinical Implications: � Most medications with renal elimination require dose adjustment when CrCl < 60 mL/min � Monitor kidney function regularly � Consider nephrology referral if declining � Adjust doses of antibiotics, anticoagulants, and other renally cleared drugs

What is creatinine clearance?

Creatinine clearance (CrCl) is a measure of kidney function that estimates the glomerular filtration rate (GFR). It indicates how efficiently the kidneys filter creatinine from the blood. Normal CrCl is 90-120 mL/min. The Cockcroft-Gault equation estimates CrCl using age, weight, gender, and serum creatinine. CrCl is used to assess kidney function, stage chronic kidney disease (CKD), and adjust medication dosages for renally eliminated drugs. Lower values indicate decreased kidney function.

How do I interpret my creatinine clearance result?

CrCl interpretation by CKD stage: >=90 mL/min = Stage 1, normal or high (kidney damage with normal GFR). 60-89 = Stage 2, mildly decreased. 30-59 = Stage 3, moderately decreased. 15-29 = Stage 4, severely decreased. <15 = Stage 5, kidney failure (dialysis may be needed). Many medications require dose adjustment when CrCl <60 mL/min. Declining CrCl over time indicates progressive kidney disease. Values <30 require nephrology referral.

What is the Cockcroft-Gault equation?

The Cockcroft-Gault equation estimates creatinine clearance: CrCl (mL/min) = [(140 - age) * weight (kg)] / [72 * serum creatinine (mg/dL)]. For females, multiply result by 0.85. Developed in 1976, it remains widely used for medication dosing despite limitations. The equation accounts for decreased muscle mass and kidney function with age. More accurate than serum creatinine alone. Alternative equations include MDRD and CKD-EPI, which estimate GFR rather than CrCl.

When should I use creatinine clearance vs GFR?

Creatinine clearance (Cockcroft-Gault) is preferred for medication dosing because most drug studies used this equation. GFR estimates (MDRD, CKD-EPI) are preferred for diagnosing and staging CKD because they are more accurate and standardized. Use CrCl for: adjusting antibiotic, chemotherapy, or other drug doses. Use eGFR for: diagnosing CKD, staging kidney disease, monitoring disease progression. Both assess kidney function but serve different clinical purposes. When in doubt, consult prescribing information or pharmacist for medication dosing.

What factors affect creatinine clearance accuracy?

Cockcroft-Gault limitations: Less accurate in obesity (use adjusted body weight), malnutrition, extreme ages, amputees, pregnancy, rapidly changing kidney function, skeletal muscle disorders. Overestimates in elderly and underestimates in obese patients. Serum creatinine affected by: muscle mass, meat intake, certain medications, hydration status. For best accuracy: use actual body weight if normal BMI, adjusted weight if obese (IBW + 0.4 * [actual - IBW]), measure creatinine when stable, consider alternatives (24-hour urine collection, eGFR) when accuracy is critical.

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