40 year male serum creatinine 1.29 mg/dl serum cystatin c 1.13mg/L calculate EGFR
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CKD-EPI 2021 creatinine cystatin C eGFR formula calculator
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All three equations are in close agreement. Here are the results:
eGFR Results — 40-year-old Male
| Equation | eGFR | CKD Stage |
|---|---|---|
| CKD-EPI 2021 Creatinine-Cystatin C (combined — most accurate) | 72.6 mL/min/1.73 m² | G2 |
| CKD-EPI 2021 Creatinine-only | 71.9 mL/min/1.73 m² | G2 |
| CKD-EPI 2012 Cystatin C-only | 71.6 mL/min/1.73 m² | G2 |
Calculation Breakdown (CKD-EPI 2021 Cr+CysC Combined)
Formula:
eGFR = 135 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^−0.544 × min(Scys/0.8, 1)^−0.323 × max(Scys/0.8, 1)^−0.778 × 0.9961^Age
Male constants: κ = 0.9, α = −0.144
| Step | Value |
|---|---|
| Scr/κ = 1.29/0.9 | 1.433 |
| min(1.433, 1)^−0.144 | 1.000 |
| max(1.433, 1)^−0.544 | 0.822 |
| Scys/0.8 = 1.13/0.8 | 1.413 |
| min(1.413, 1)^−0.323 | 1.000 |
| max(1.413, 1)^−0.778 | 0.764 |
| 0.9961^40 | 0.855 |
| 135 × 1 × 0.822 × 1 × 0.764 × 0.855 | ≈ 72.6 |
Interpretation
- eGFR ≈ 72.6 mL/min/1.73 m² → CKD Stage G2 (mildly decreased kidney function)
- The close concordance across all three equations (71.6–72.6) increases confidence in this estimate — discordant creatinine vs. cystatin C eGFRs would suggest a non-GFR determinant affecting one marker (e.g., muscle wasting falsely lowering creatinine, or inflammation falsely raising cystatin C).
- The combined Cr + CysC equation is the most precise and is preferred when cystatin C is available (KDIGO 2024 guidelines).
- At this eGFR, CKD diagnosis requires a confirmatory repeat measurement ≥ 3 months apart plus evidence of kidney damage (albuminuria, structural abnormality, etc.); an isolated mildly reduced eGFR alone does not establish CKD.
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