Creatinine Clearance

CRNA Study Suite · Cockcroft-Gault
Patient
Normal Ranges
ParameterRange
CrCl (male)90-120 mL/min
CrCl (female)80-110 mL/min
Creatinine (male)0.7-1.3 mg/dL
Creatinine (female)0.5-1.1 mg/dL
Age-related decline~1 mL/min/yr after 40
(Morse, 2023, pp. 745, 751)
Result
CrCl
--
mL/min
CKD Stage
--
estimate
Expected for Age
--
mL/min
Calculation Breakdown
Cockcroft-Gault Equation
CrCl (mL/min) = [(140 − age) × weight (kg)] / [72 × SCr (mg/dL)]; × 0.85 if female
--
CrCl = -- mL/min
(Morse, 2023, p. 751)
Limitations
• Overestimates GFR in obesity (uses actual weight) — consider IBW or ABW for obese patients
• Does not adjust for BSA
• Less accurate at extremes of age and weight
• Unstable creatinine (rising/falling) → formula unreliable (use 24-hr urine collection instead)
(Morse, 2023, p. 751)
CKD Staging (KDIGO, estimate from CrCl)
StageCrCl (mL/min)Meaning
1≥90Normal (w/ kidney damage markers)
260-89Mildly decreased
3a45-59Mild-moderate decrease
3b30-44Moderate-severe decrease
415-29Severely decreased
5<15Kidney failure / dialysis
References

Morse, C. Y. (2023). Renal anatomy, physiology, pathophysiology, and anesthesia management. In S. Elisha, J. S. Heiner, & J. J. Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 742-769). Elsevier.

How this works

The Cockcroft-Gault equation

Creatinine clearance estimates glomerular filtration rate and guides dose adjustment for renally cleared drugs. The equation is CrCl (mL/min) = [(140 - age) x weight (kg)] / [72 x serum creatinine (mg/dL)], multiplied by 0.85 for female patients (Morse, 2023, p. 751). It estimates clearance rather than true GFR and overestimates in obese patients because it uses actual body weight. Normal is 90 to 120 mL/min in men and 80 to 110 mL/min in women (Morse, 2023, p. 753).

Why it matters intraoperatively

Renal clearance of drugs falls in proportion to GFR decline, prolonging duration of action (Morse, 2023, p. 760). Morphine needs a 50 to 75% reduction and is avoided in ESRD, pancuronium is avoided (80% renal excretion), and sugammadex is avoided if GFR is below 30, while fentanyl, remifentanil, and cisatracurium need little to no adjustment (Morse, 2023, pp. 760-762).

References

Morse, C. Y. (2023). Renal anatomy, physiology, pathophysiology, and anesthesia management. In Elisha, Heiner, & Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 742-769). Elsevier.