肌酐清除率计算器 — Cockcroft-Gault 公式
Use this free creatinine clearance calculator to estimate kidney function using the Cockcroft-Gault equation. Enter age, body weight, serum creatinine, and biological sex to calculate CrCl (mL/min) and determine the corresponding CKD stage. This tool is for educational purposes only — consult a healthcare professional for clinical decisions.
Cockcroft-Gault Equation
Enter patient details to estimate creatinine clearance (CrCl) as a measure of kidney function.
Use actual body weight (IBW or adjusted body weight may be used in clinical settings for obese patients).
Normal range: 0.6–1.2 mg/dL (males), 0.5–1.1 mg/dL (females).
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常见问题
什么是肌酐清除率（CrCl）？
肌酐清除率（CrCl）是估算肾脏每分钟过滤血液量的指标，以 mL/min 表示。它根据血清肌酐水平和患者特征计算。数值越高表示肾功能越好。健康成年人的正常 CrCl 约为 90-120 mL/min。
什么是 Cockcroft-Gault 方程？
Cockcroft-Gault 方程是估算肌酐清除率的公式：CrCl = ((140 − 年龄) × 体重 kg) / (72 × 血清肌酐 mg/dL)。对于女性，结果乘以 0.85 以考虑较低的肌肉质量。该方程发表于 1976 年，至今仍是药物剂量指南中使用的标准公式。
正常的肌酐清除率是多少？
成年人的正常肌酐清除率通常 ≥90 mL/min。60-89 mL/min 表示肾功能轻度降低；30-59 mL/min 表示中度降低；15-29 mL/min 表示重度损害；低于 15 mL/min 表示肾衰竭，可能需要透析。
CrCl 和 eGFR 有什么区别？
通过 Cockcroft-Gault 计算的肌酐清除率（CrCl）主要用于药物剂量调整，以 mL/min 表示（绝对值，未标准化至体表面积）。通过 CKD-EPI 方程估算的 GFR（eGFR）用于慢性肾脏病分期，以 mL/min/1.73 m² 表示。大多数 FDA 药物标签使用 Cockcroft-Gault 方程的 CrCl 阈值进行剂量调整。
为什么女性的公式要乘以 0.85？
相同体重和年龄的女性通常比男性肌肉量更少。由于肌酐是肌肉代谢的副产品，女性每日产生的肌酐较少。这意味着相同的血清肌酐水平在女性中对应更低的实际 CrCl。0.85 系数（降低 15%）用于校正这种系统性差异。
在 Cockcroft-Gault 公式中应使用哪种体重？
对于正常体重患者，使用实际体重（ABW）。对于肥胖患者（体重超过理想体重 30% 以上），临床医生通常使用理想体重（IBW）或调整体重（ABW = IBW + 0.4 × (实际体重 - IBW)），以避免高估肾功能。对于体重偏轻的患者，一般使用实际体重。
肌酐清除率何时用于药物剂量？
CrCl 用于调整经肾脏清除药物的剂量，包括许多抗生素（万古霉素、庆大霉素）、抗凝药（达比加群、利伐沙班）、糖尿病药物（二甲双胍）、抗病毒药、心脏药物（地高辛）和化疗药物。FDA 和药品制造商根据 Cockcroft-Gault 方程指定 CrCl 阈值。
此计算器可用于儿童或孕妇吗？
不可以。Cockcroft-Gault 方程在成年男性中得到验证，不推荐用于儿科患者（儿童首选 Schwartz 方程）或妊娠期间（生理变化会显著改变肾功能和肌酐产生）。对于这些人群，请咨询专科医生。
About the Creatinine Clearance Calculator
About This Calculator
Creatinine clearance (CrCl) is an estimate of the glomerular filtration rate (GFR) — how well the kidneys filter waste products from the blood. It is measured in mL/min and is one of the most commonly used clinical markers of kidney function.
This calculator uses the Cockcroft-Gault (CG) equation, introduced in 1976 by Donald W. Cockcroft and M. Henry Gault. It remains widely used in pharmacology for drug dosing adjustments because most drug labeling was developed using this formula.
Inputs required: patient's age (years), body weight (kg), serum creatinine (mg/dL), and biological sex. The result is expressed in mL/min.
Cockcroft-Gault Formula
The Cockcroft-Gault equation calculates creatinine clearance as follows:
CrCl = ((140 − Age) × Weight) / (72 × Serum Creatinine)
For females: CrCl × 0.85
Where:
- Age — Patient age in years. Older age is associated with reduced kidney function.
- Weight — Body weight in kilograms. Actual body weight is used for most patients; ideal body weight (IBW) or adjusted body weight (ABW) is used for obese patients in clinical practice.
- Serum Creatinine — Lab-measured creatinine concentration in mg/dL. Higher creatinine indicates worse kidney function.
- 72 — A normalizing constant derived empirically from the original dataset.
- 0.85 multiplier (females) — Women typically have lower muscle mass than men, producing less creatinine. This correction factor accounts for that difference.
The formula was derived from a study of 249 adult male patients and subsequently validated in numerous clinical populations. The 0.85 correction for females was added to account for the observed sex-based difference in creatinine production.
CKD Stages Table
Chronic Kidney Disease (CKD) is classified by GFR (or estimated CrCl). The following table shows the standard staging used in clinical practice (based on KDIGO 2012 guidelines):
| CKD Stage | CrCl / GFR (mL/min) | Description | Clinical Action |
|---|---|---|---|
| Normal | ≥90 | Normal or high kidney function | Monitor for risk factors (diabetes, hypertension) |
| Mild (G2) | 60–89 | Mildly reduced kidney function | Manage risk factors; annual monitoring |
| Moderate (G3) | 30–59 | Moderately reduced kidney function | Nephrology referral often recommended; adjust drug doses |
| Severe (G4) | 15–29 | Severely reduced kidney function | Nephrology follow-up; prepare for renal replacement therapy |
| Failure (G5) | <15 | Kidney failure | Dialysis or kidney transplant evaluation |
Note: Official KDIGO staging uses eGFR (CKD-EPI equation), not CrCl directly. Consult a nephrologist for formal CKD staging and management.
CrCl vs eGFR — Which to Use?
Although both creatinine clearance (CrCl) and estimated GFR (eGFR) assess kidney function using serum creatinine, they are calculated differently and serve different clinical purposes:
| Feature | CrCl (Cockcroft-Gault) | eGFR (CKD-EPI) |
|---|---|---|
| Primary use | Drug dosing adjustments | CKD staging and monitoring |
| Units | mL/min (absolute) | mL/min/1.73 m² (normalized) |
| Body size adjustment | Not normalized to BSA | Normalized to 1.73 m² BSA |
| Recommended by FDA for | Drug dosing guidelines | Disease staging |
| Accuracy | Good for drug dosing; less accurate in obese or elderly | More accurate for GFR estimation in general population |
The FDA and most drug labeling reference the Cockcroft-Gault CrCl for dose adjustments. Use eGFR (CKD-EPI) for CKD staging per KDIGO guidelines. When in doubt, consult a nephrologist or clinical pharmacist.
Limitations of the Cockcroft-Gault Equation
The Cockcroft-Gault equation provides a useful estimate but has known limitations:
- Unstable kidney function — The formula assumes stable serum creatinine. During acute kidney injury or rapid deterioration, the equation may significantly overestimate CrCl.
- Extremes of age — In elderly patients (>80 years), CrCl may be overestimated because muscle mass (and creatinine production) declines with age faster than kidney function.
- Obesity — Using actual body weight in obese patients may overestimate CrCl. Clinicians often substitute ideal body weight (IBW) or adjusted body weight (ABW).
- Malnutrition / cachexia — Very low muscle mass (e.g., in cancer or severe illness) leads to low serum creatinine, which can overestimate kidney function.
- Pediatric patients — The formula was validated in adults only. The Schwartz equation is preferred for children.
- Pregnancy — Physiologic changes in pregnancy alter creatinine production and GFR; specialized formulas are needed.
- Race and ethnicity — Original creatinine-based formulas may have race-based correction factors. The 2021 CKD-EPI equation removed race as a variable to reduce health disparities.
Drug Dosing Applications
Creatinine clearance is essential for adjusting doses of renally-cleared medications. Many drugs accumulate to toxic levels when kidney function is impaired. Common drug classes requiring CrCl-based dose adjustment include:
- Antibiotics — Vancomycin, gentamicin, nitrofurantoin, trimethoprim-sulfamethoxazole (renally excreted; accumulation causes toxicity)
- Anticoagulants — Dabigatran, rivaroxaban, apixaban (direct oral anticoagulants; dose reduction or contraindication at low CrCl)
- Diabetes medications — Metformin (contraindicated at CrCl <30; risk of lactic acidosis), SGLT-2 inhibitors (reduced efficacy and safety concerns at low CrCl)
- Antiviral medications — Acyclovir, valacyclovir, ganciclovir (dose adjustment required to prevent crystalluria and neurotoxicity)
- Cardiac drugs — Digoxin, atenolol, sotalol (renally cleared; toxicity risk at reduced CrCl)
- Chemotherapy agents — Carboplatin, cisplatin, methotrexate (renal dosing critical to prevent severe toxicity)
- Analgesics — Morphine (active metabolites accumulate), gabapentin, pregabalin
Always verify drug-specific dosing thresholds with current prescribing information or a clinical pharmacist. CrCl thresholds for dose adjustment vary by drug.
Medical Disclaimer
This creatinine clearance calculator and all information on this page are provided for educational and informational purposes only. The results are estimates and are not a substitute for clinical laboratory measurements, professional diagnosis, or medical advice. Kidney function assessment and drug dosing in renal impairment require individualized clinical judgment by a qualified healthcare professional. If you have concerns about your kidney health, consult a physician or nephrologist. For emergencies, call 911 or your local emergency number.