Health

Creatinine Clearance Calculator

Estimate kidney function using the Cockcroft-Gault equation.

Quick Answer

A 45-year-old male weighing 70 kg with serum creatinine of 1.0 mg/dL has an estimated CrCl of 92 mL/min (normal). Values below 60 indicate moderate kidney disease.

Normal: 0.6-1.2 mg/dL (male), 0.5-1.1 mg/dL (female)

Disclaimer: This calculator is for educational purposes only. Estimated CrCl should be interpreted by a healthcare professional in clinical context. The Cockcroft-Gault equation has limitations in elderly, obese, and malnourished patients. Do not use this tool to make medication decisions without consulting your doctor or pharmacist.

About This Tool

The Creatinine Clearance Calculator uses the Cockcroft-Gault equation to estimate how well your kidneys filter waste from the blood. It is the standard formula used by pharmacists and physicians for drug dosing adjustments in patients with kidney impairment.

Creatinine is a waste product produced by normal muscle metabolism. Healthy kidneys filter it efficiently from the blood into urine. When kidney function declines, creatinine builds up in the blood. By measuring serum creatinine and factoring in age, weight, and sex, the Cockcroft-Gault equation provides a practical estimate of kidney filtration capacity.

Limitations

The equation may overestimate function in obese patients (use ideal body weight) and underestimate in elderly or malnourished patients. It was developed in a primarily male population. For staging chronic kidney disease, the CKD-EPI equation is now preferred. However, Cockcroft-Gault remains the standard for drug dosing because most pharmaceutical studies used this equation.

Frequently Asked Questions

What is creatinine clearance?
Creatinine clearance (CrCl) estimates how well your kidneys filter creatinine from the blood, measured in mL/min. It serves as a proxy for glomerular filtration rate (GFR). Normal CrCl is approximately 90-120 mL/min for healthy adults. Lower values indicate reduced kidney function and may require medication dose adjustments.
What is the Cockcroft-Gault equation?
The Cockcroft-Gault equation estimates creatinine clearance using age, weight, serum creatinine, and sex: CrCl = [(140 - age) x weight in kg] / (72 x serum creatinine). For females, the result is multiplied by 0.85. It was developed in 1976 and remains widely used for drug dosing adjustments, though the CKD-EPI equation is now preferred for staging chronic kidney disease.
What do the kidney function stages mean?
G1 (CrCl 90+): Normal. G2 (60-89): Mildly decreased, usually no symptoms. G3a (45-59): Mild-moderate decrease, may need monitoring. G3b (30-44): Moderate-severe decrease, complications may appear. G4 (15-29): Severely decreased, prepare for possible dialysis. G5 (<15): Kidney failure, dialysis or transplant typically needed.
What causes elevated creatinine levels?
High serum creatinine can indicate kidney disease, dehydration, high protein diet, intense exercise, certain medications (ACE inhibitors, NSAIDs), urinary tract obstruction, or conditions that reduce blood flow to the kidneys. Very muscular individuals may have naturally higher creatinine. A single elevated reading should be confirmed with repeat testing.
Why is CrCl important for medication dosing?
Many drugs are eliminated through the kidneys. When kidney function is reduced, drugs clear more slowly, potentially reaching toxic levels. Medications like metformin, antibiotics, anticoagulants, and many others require dose adjustments based on CrCl. The Cockcroft-Gault equation is specifically used for drug dosing because most drug studies used this equation to determine dose adjustments.

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