Creatinine clearance — renal function reference.
Applies to / doesn’t apply to9
Applies to: Adults with stable renal function. Derived in 249 patients aged 18–92, validated in 236 against 24-hour urine collections (r = 0.83) in a cohort that was approximately 96% male.
- Unstable or rapidly changing creatinine — the formula assumes a steady state.
- Dialysis or end-stage renal disease.
- Children — it was derived in adults.
- Pregnancy — not validated (Wiles 2019).
- On a drug that inhibits tubular secretion of creatinine: trimethoprim, cimetidine, cobicistat, dolutegravir or ritonavir.
- High muscle mass or creatine supplementation.
- Sarcopenia, paralysis, spinal cord injury, or limb amputation.
- Cirrhosis.
- Acute fluid shifts or third-spacing, which make the weight input itself unreliable.
An exact age is required — age is a term in the formula, not a threshold.
A factor of 0.85 is applied for female sex, as in the original paper.
Used to select the weight basis (actual / ideal / adjusted body weight) by BMI — it is not a term in the formula itself.
Entered as measured. Low values are never rounded up.
What this score estimates
Estimates creatinine clearance from age, weight, height, sex and serum creatinine. Height sets the BMI, which selects the weight basis fed into the formula — actual body weight below BMI 18.5, ideal body weight (Devine) from 18.5 to under 30, and adjusted body weight at 30 or above. Reported in mL/min as a whole number.
Pearls & pitfalls12
- Reported in mL/min, not mL/min/1.73m². It is not comparable to an MDRD or CKD-EPI eGFR read off the same chart without adjusting for body surface area.
- Overestimates true GFR by 10–20% relative to measured clearance, because creatinine is secreted by the renal tubules as well as filtered.
- Fitted to older Jaffe-type assays that read high. Modern IDMS-traceable assays read lower, so the same patient yields a value roughly 10–20% above what the formula was calibrated for.
- The weight basis is chosen from BMI (actual / ideal / adjusted body weight). At extremes of body habitus, weight still misrepresents creatinine-generating muscle mass in both directions.
- Drugs that inhibit tubular secretion of creatinine — trimethoprim, cimetidine, cobicistat, dolutegravir, ritonavir — raise serum creatinine without changing true GFR, so the estimate falls even though kidney function has not.
- High muscle mass or creatine supplementation raises serum creatinine independently of GFR, which makes the estimate read low.
- Acute fluid shifts or third-spacing in critical illness make the weight input itself unreliable, so the estimate cannot be trusted in that setting.
- Substantially overestimates clearance where muscle mass is low — sarcopenia, paralysis, spinal cord injury, limb amputation — and in cirrhosis, where reduced hepatic creatinine synthesis lowers serum creatinine. KDIGO 2024 advises caution wherever muscle mass is abnormal for the patient’s size.
- Not validated in pregnancy, where increased glomerular filtration and plasma volume make creatinine-based estimates unreliable (Wiles 2019).
- Do not use in unstable or rapidly changing creatinine, in dialysis or end-stage renal disease, or in children — it was derived in adults.
- The 0.85 factor for female sex is in the original paper, but was not empirically derived from its near-all-male cohort.
- Current guidance favours a validated eGFR equation over this one for assessing kidney function; Cockcroft–Gault persists mainly because many drug labels were written against it.
What the guidelines say1
US drug labels commonly express renal dose adjustments against Cockcroft–Gault creatinine clearance in mL/min, which is why this estimate is provided in mL/min rather than as an eGFR.
Guideline positions are stated as published. Curie.MD Calc does not publish treatment direction.
Where this comes from5
- Cockcroft DW, Gault MH. Nephron. 1976;16(1):31-41. View source ↗
- Winter MA, Guhr KN, Berg GM. Pharmacotherapy. 2012;32(7):604-12. View source ↗
- Brown DL, Masselink AJ, Lalla CD. Ann Pharmacother. 2013;47(7-8):1039-44. View source ↗
- Wiles K, Chappell L, Clark K, et al. BMC Nephrol. 2019;20(1):401. View source ↗
- KDIGO 2024 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int. 2024;105(4S):S117-S314. View source ↗