Calculadora de Clearance de Creatinina (Cockcroft-Gault)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
ClCr = ((140 − idade)·peso·f) / (72·creatinina)
About this calculator
The Creatinine Clearance Calculator using the Cockcroft-Gault formula estimates the glomerular filtration rate (GFR) based on simple data such as age, weight, serum creatinine, and sex. The formula is: ClCr = ((140 - age) × weight × f) / (72 × creatinine), where f is 1 for men and 0.85 for women. The result is expressed in mL/min and indicates the volume of plasma from which the kidneys can clear creatinine per minute.
This calculator is widely used in clinical practice to adjust doses of renally excreted drugs, especially in elderly patients or those with chronic kidney disease. For example, when prescribing antibiotics like vancomycin or anticoagulants, creatinine clearance helps avoid toxicity or underdosing. It is also useful for assessing renal function before contrast exams or surgeries.
The Cockcroft-Gault formula was developed in the 1970s and remains a standard tool despite limitations. It tends to overestimate GFR in obese or edematous patients because it uses total body weight. For patients with very high weight, it is recommended to use ideal or adjusted body weight. Additionally, serum creatinine can be influenced by diet, muscle mass, and medications such as cimetidine.
Important: this calculator does not replace medical evaluation. Abnormal results should be interpreted by a professional. For patients with unstable renal function (e.g., in the ICU) or extremes of age (children, very elderly), other formulas like CKD-EPI may be more appropriate. Always consider the complete clinical context.
Frequently asked questions
What does a low creatinine clearance mean?
It indicates that the kidneys are filtering less creatinine than normal, suggesting reduced kidney function. Values below 60 mL/min per 1.73 m² for more than 3 months characterize chronic kidney disease.
Do I need to fast for the creatinine test?
Fasting is not required, but avoid excessive red meat consumption in the 24 hours before the test, as it can temporarily raise creatinine. Also inform your doctor about any medications you are taking.
Does the calculator work for children?
No. The Cockcroft-Gault formula is not validated for children (under 18 years). For children, use formulas such as Schwartz or Bedside Schwartz, which consider height and creatinine.
What is the difference between creatinine clearance and GFR?
Creatinine clearance is an estimate of GFR, but not exactly the same. GFR is the gold standard, measured with markers like inulin or iohexol. Clearance overestimates GFR because creatinine is also secreted by the renal tubules.
Can I use ideal body weight instead of actual weight?
Yes, especially in obese patients (BMI > 30). Ideal body weight can be calculated using formulas: men: 50 kg + 0.9 kg for each cm above 152.4 cm; women: 45.5 kg + 0.9 kg for each cm above 152.4 cm. Some adjustments use adjusted body weight = ideal weight + 0.4 × (actual weight - ideal weight).