Calculate creatinine clearance using the Cockcroft-Gault formula. Assess kidney function for drug dosing.
Calculate kidney function using Cockcroft-Gault.
The Creatinine Clearance (CrCl) Calculator estimates kidney function using the Cockcroft-Gault formula, which remains the preferred method for adjusting medication dosages in patients with kidney impairment. Unlike eGFR which assesses disease stage, creatinine clearance is specifically used for drug dosing decisions because most pharmaceutical studies use this measure.
Creatinine is a waste product from normal muscle metabolism that is filtered out by the kidneys. When kidney function declines, creatinine accumulates in the blood and its clearance rate decreases. Measuring how quickly creatinine is cleared from the blood provides a reliable estimate of overall kidney filtration capacity. This is critical for medications that are eliminated by the kidneys—incorrect dosing can lead to toxicity or ineffectiveness.
The Cockcroft-Gault formula, developed in 1976, remains widely used in clinical practice despite newer equations like CKD-EPI for GFR. It accounts for age (kidney function naturally declines), weight (more muscle = more creatinine production), sex (women have less muscle mass), and serum creatinine level. For obese patients, adjusted body weight may be used for more accurate results.
Result in mL/min (not adjusted for body surface area like eGFR).
| Category | CrCl (mL/min) | Clinical Significance |
|---|---|---|
| Normal | ≥90 | No dose adjustment needed |
| Mild Impairment | 60-89 | Some drugs may need adjustment |
| Moderate Impairment | 30-59 | Most renally-cleared drugs adjusted |
| Severe Impairment | 15-29 | Significant dose reductions needed |
| End-Stage | <15 | Contraindicated for many drugs |
A 60-year-old woman, 65 kg, creatinine 1.0 mg/dL: CrCl = [(140-60) × 65] ÷ [72 × 1.0] × 0.85 = 5,200 ÷ 72 × 0.85 = 61 mL/min — mild impairment, check medication inserts.
Related tools: GFR Calculator for kidney disease staging, BSA Calculator for body surface area, and BMI Calculator for weight assessment.
Cockcroft-Gault: CrCl = [(140-age) × weight(kg)] ÷ [72 × creatinine(mg/dL)]. Multiply by 0.85 for females. Result in mL/min. Used for drug dosing adjustments.
Normal: 90-140 mL/min for young adults. Decreases ~1 mL/min/year after 40. 60-89 is mild impairment, 30-59 moderate, <30 severe. Values guide medication dosing.
GFR (eGFR) assesses kidney disease staging. CrCl is used for drug dosing. CrCl includes tubular secretion, slightly overestimating GFR. Different formulas serve different clinical purposes.