Renal function
Estimated GFR (CKD-EPI 2021)eGFR
Serum-creatinine–based estimate of glomerular filtration rate; the operating definition of CKD stage.
Sample
Calculated from creatinine, age, and sex
Clinical reference range
90 to — mL/min/1.73m²
Normal
Conv: 90–— mL/min/1.73m²
Biology
What it measures
CKD-EPI 2021 uses creatinine, age, and sex (no race coefficient). Combined creatinine-cystatin C version (CKD-EPIcr-cys) is more accurate at extremes.
Clinical use
Why we order it
Stage CKD (G1 ≥90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, G5 <15). Drug dosing and renal-care planning use eGFR.
Lens · Clinical
Interpretation by lens
Clinical interpretation
CKD requires either eGFR <60 OR markers of kidney damage (UACR ≥30 mg/g, hematuria, structural abnormalities) for ≥3 months.
Pitfalls
Pre-analytic & interpretation traps
- !Equations assume steady state — invalid in AKI.
- !Inaccurate at GFR >60 with low muscle mass; use cystatin C or measured GFR.
Follow-up orders
Logical next-step labs
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