Creatinine Clearance vs GFR
Creatinine clearance (CrCl) estimates how quickly creatinine is cleared from blood by kidneys. It's similar to GFR but uses the older Cockcroft-Gault equation. CrCl is still commonly used for drug dosing adjustments in renal impairment.
When CrCl is Used
Medication dosing (especially antibiotics, anticoagulants, chemotherapy). Assessing kidney function before contrast dyes. Some clinical trials use CrCl rather than eGFR. CrCl may overestimate GFR in obese patients and underestimate in elderly with low muscle mass.
Medication Adjustments
CrCl >80: Usually normal dosing
CrCl 50-80: Some drugs need adjustment
CrCl 30-50: Many drugs need dose reduction
CrCl 10-30: Most drugs need adjustment
CrCl <10: Dialysis-dependent dosing
Always check drug-specific guidelines for renal dosing.
Quick Tips
- BMI alone doesn't reflect overall health
- TDEE varies based on activity level
- Consult a healthcare professional for medical decisions
Frequently Asked Questions
Use actual weight unless patient is obese (BMI >30), then consider adjusted weight.
Muscle mass decreases with age, reducing creatinine production. Also, kidney function naturally declines.
Yes, still widely used for drug dosing despite being older than CKD-EPI equation.
No, only renally-cleared drugs. Check prescribing information for each medication.
Yes, with hydration status and acute illness. Recalculate if clinical status changes.