Formula
CrCl (mL/min) = [(140 − Age) × Weight × F] / [72 × Scr (mg/dL)]
Where F = 1.0 for males, 0.85 for females
IBW — Devine Formula:
Male: 50 + 2.3 × (height in inches − 60)
Female: 45.5 + 2.3 × (height in inches − 60)
Adjusted BW (AdjBW):
AdjBW = IBW + 0.4 × (Actual BW − IBW)
Use when actual BW > 30% above IBW (obese patients)
The Devine formula is used for IBW in the Cockcroft-Gault context (not the Lorentz formula). For patients who weigh less than IBW, use actual body weight. For obese patients (>30% above IBW), adjusted body weight is recommended to avoid overestimating CrCl.
CKD Staging (GFR Categories)
| CrCl (mL/min) | CKD Stage | Description |
|---|
| ≥ 90 |
G1 — Normal or High |
Normal kidney function; treat underlying condition if CKD markers present |
| 60 – 89 |
G2 — Mildly Decreased |
Mild reduction; monitor annually; address cardiovascular risk factors |
| 45 – 59 |
G3a — Mild-Moderate |
Nephrology referral considered; review and adjust drug dosing |
| 30 – 44 |
G3b — Moderate-Severe |
Nephrology involvement; significant drug dosing adjustments required |
| 15 – 29 |
G4 — Severely Decreased |
Prepare for renal replacement therapy; extensive medication review |
| < 15 |
G5 — Kidney Failure |
Dialysis or transplantation indicated; hold nephrotoxic agents |
Cockcroft-Gault vs CKD-EPI
The two equations serve distinct clinical purposes and should not be used interchangeably:
- Cockcroft-Gault (CG): Best suited for drug dosing. Used by regulatory agencies (FDA, EMA) and pharmacokinetic studies as the reference method. It estimates CrCl in mL/min and accounts for body weight, which is important for weight-dependent dosing.
- CKD-EPI: Preferred for CKD staging and epidemiological studies. Estimates GFR in mL/min/1.73m² (normalised to body surface area). More accurate across a wide GFR range, particularly at higher GFR values.
- When to use CG: Drug dose adjustment for renally-cleared medications (antibiotics, chemotherapy, LMWH, DOACs, NSAIDs, metformin); MDRD and CKD-EPI are not recommended by most formularies for drug dosing.
Key Drugs Requiring CG-Based Dosing
- Antibiotics: Aminoglycosides, vancomycin (dose and interval), beta-lactams, fluoroquinolones, nitrofurantoin (avoid <30 mL/min)
- Anticoagulants: Enoxaparin (LMWH) and all DOACs (dabigatran, rivaroxaban, apixaban, edoxaban) — each has specific CrCl thresholds for dose reduction or avoidance
- Chemotherapy: Carboplatin (Calvert formula), methotrexate, bleomycin — CrCl directly determines dosing
- Other: Metformin (contraindicated <30 mL/min), digoxin, gabapentin/pregabalin, allopurinol, colchicine, spironolactone
- Contrast media: CG or CKD-EPI used to screen for contrast-induced nephropathy risk before IV iodinated contrast administration
References
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31–41.
- Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650–655.
- Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate glomerular filtration rate. Ann Intern Med. 2009;150(9):604–612. (CKD-EPI)
- KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int Suppl. 2013;3(1):1–150.