Creatinine Clearance

Creatinine Clearance Calculator

Cockcroft-Gault Equation

Diagnostic Parameters

Age (Years)

Total Weight (kg)

Serum Creatinine (mg/dL)

Biological Sex

Cockcroft-Gault remains the standard for drug dosing.

Drug Clearance Engine

Enter metrics to execute Cockcroft-Gault dosing verification.

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Core Clinical Uses

Primary method for renal drug dosing adjustment (FDA labeling standard).

Estimation of kidney function in stable adult patients using serum creatinine.

Baseline renal function assessment prior to initiating nephrotoxic medications.

Monitoring renal function trends in chronic kidney disease (CKD).

Dose individualisation for narrow therapeutic index drugs (e.g., aminoglycosides, vancomycin, lithium, digoxin).

High-Impact Clinical Scenarios

Sepsis and ICU patients receiving renally cleared antibiotics.

HIV/TB patients on tenofovir, aminoglycosides, or amphotericin B.

Elderly patients with polypharmacy and reduced muscle mass.

Oncology patients receiving nephrotoxic chemotherapy.

When NOT to Use

Avoid use in acute kidney injury (AKI) or rapidly changing creatinine levels. Not validated in children, pregnancy, or patients with extreme body composition (e.g., amputees, severe obesity) without appropriate adjustments. In ICU patients, may significantly misrepresent true GFR.

How it Works

Cockcroft-Gault Equation

CrCl (Male) = [(140 − Age) × Weight (kg)] / [72 × Serum Creatinine (mg/dL)] CrCl (Female) = CrCl × 0.85

Physiological Basis

Creatinine is generated from muscle metabolism at a relatively constant rate. The formula estimates creatinine production using age, sex, and body weight as proxies for muscle mass. Clearance is then inferred by dividing estimated production by serum creatinine concentration.

Key Assumptions

Steady-state creatinine production and excretion.

Stable renal function over preceding 24–48 hours.

Normal relationship between muscle mass and total body weight.

Comparison with Other GFR Estimators

Cockcroft-Gault	Drug dosing standard; influenced by weight.
CKD-EPI	Most accurate for GFR estimation; preferred for CKD staging.
MDRD	Less accurate at higher GFR (>60 mL/min).
24-hour Creatinine Clearance	Gold standard but impractical and error-prone.

Clinical Pearls

Weight Selection (Critical for Accuracy)

Underweight or normal BMI: Use Actual Body Weight (ABW).

Obese (BMI > 30): Use Adjusted Body Weight (AjBW = IBW + 0.4 × [TBW − IBW]).

Morbid obesity: Consider capping weight or using alternative methods (e.g., CKD-EPI).

Interpretation Bands

≥ 90 mL/min	Normal renal function
60–89 mL/min	Mild impairment
30–59 mL/min	Moderate impairment
15–29 mL/min	Severe impairment
< 15 mL/min	Kidney failure (consider dialysis)

Major Pitfalls

Overestimation of GFR due to tubular secretion of creatinine.

Low muscle mass (elderly, cachexia, liver disease) → falsely elevated CrCl.

High muscle mass (bodybuilders) → underestimated renal impairment.

Recent cooked meat ingestion → transient creatinine elevation.

Fluid overload or dehydration distorting serum creatinine concentration.

Advanced Clinical Pearl

In critically ill or septic patients, Cockcroft-Gault may significantly overestimate renal function. Consider using dynamic markers (e.g., urine output trends, cystatin C if available) and dose conservatively.

Next Steps

Drug Dosing Strategy

Match CrCl to drug-specific dosing thresholds (check label or guidelines).

Adjust dosing interval (e.g., 12-hourly → 24-hourly) or reduce dose.

Avoid nephrotoxic drugs where possible (NSAIDs, aminoglycosides, contrast).

Use therapeutic drug monitoring (TDM) for high-risk drugs.

Reassess renal function frequently in unstable patients.

Common Drug Adjustments

Aminoglycosides	Extend dosing interval (extended-interval dosing preferred).
Vancomycin	Dose based on trough levels and CrCl.
Tenofovir	Reduce frequency if CrCl < 50 mL/min.
Metformin	Avoid if CrCl < 30 mL/min (risk of lactic acidosis).

Diagnostic Follow-up

If CrCl < 60 mL/min for > 3 months → evaluate for CKD.

Order urine ACR and urinalysis.

Assess for reversible causes (dehydration, obstruction, drugs).

Refer to nephrology if CrCl < 30 mL/min or rapid decline.

Last Comprehensive Review: 2026-07-17

In Recent Clinical News

Scanning Medical Journals

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Creatinine Clearance

When to Use

Core Clinical Uses

High-Impact Clinical Scenarios

When NOT to Use

How it Works

Cockcroft-Gault Equation

Physiological Basis

Key Assumptions

Comparison with Other GFR Estimators

Clinical Pearls

Weight Selection (Critical for Accuracy)

Interpretation Bands

Major Pitfalls

Advanced Clinical Pearl

Next Steps

Drug Dosing Strategy

Common Drug Adjustments

Diagnostic Follow-up

The Evidence

Foundational Study

Prediction of creatinine clearance from serum creatinine.

Guideline Context

Origins & History

Historical Development

Clinical Impact

In Recent Clinical News

Creatinine Clearance

When to Use

Core Clinical Uses

High-Impact Clinical Scenarios

When NOT to Use

How it Works

Cockcroft-Gault Equation

Physiological Basis

Key Assumptions

Comparison with Other GFR Estimators

Clinical Pearls

Weight Selection (Critical for Accuracy)

Interpretation Bands

Major Pitfalls

Advanced Clinical Pearl

Next Steps

Drug Dosing Strategy

Common Drug Adjustments

Diagnostic Follow-up

The Evidence

Foundational Study

Prediction of creatinine clearance from serum creatinine.

Guideline Context

Origins & History

Historical Development

Clinical Impact

In Recent Clinical News