CKD-EPI 2021 creatinine cystatin C eGFR formula calculator

python3 << 'EOF' import math # Patient: 40-year-old MALE # Scr = 1.29 mg/dL # Scys = 1.13 mg/L # Age = 40 Scr = 1.29 Scys = 1.13 age = 40 sex = "male" # ─── 1. CKD-EPI 2021 Creatinine-Only equation ─────────────────────────────── # eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^-1.200 × 0.9938^Age [× 1.012 if female] # Male: κ = 0.9, α = -0.302 kappa_cr = 0.9 alpha_cr = -0.302 ratio_cr = Scr / kappa_cr # 1.29 / 0.9 = 1.4333... min_cr = min(ratio_cr, 1.0) # = 1.0 (since ratio > 1) max_cr = max(ratio_cr, 1.0) # = 1.4333 egfr_cr = 142 * (min_cr ** alpha_cr) * (max_cr ** -1.200) * (0.9938 ** age) print(f"=== CKD-EPI 2021 Creatinine-Only ===") print(f" Scr/κ = {ratio_cr:.4f}") print(f" min(Scr/κ,1)^α = {min_cr}^{alpha_cr} = {min_cr**alpha_cr:.6f}") print(f" max(Scr/κ,1)^-1.2 = {max_cr:.4f}^-1.2 = {max_cr**-1.2:.6f}") print(f" 0.9938^{age} = {0.9938**age:.6f}") print(f" eGFR (cr only) = {egfr_cr:.2f} mL/min/1.73m²\n") # ─── 2. CKD-EPI 2021 Creatinine-Cystatin C combined equation ───────────────── # eGFRcr-cys = 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 [× 0.963 if female] # Male: κ = 0.9, α = -0.144 kappa_cr2 = 0.9 alpha_cr2 = -0.144 ratio_cr2 = Scr / kappa_cr2 # 1.29/0.9 = 1.4333 min_cr2 = min(ratio_cr2, 1.0) # 1.0 max_cr2 = max(ratio_cr2, 1.0) # 1.4333 ratio_cys = Scys / 0.8 # 1.13/0.8 = 1.4125 min_cys = min(ratio_cys, 1.0) # 1.0 max_cys = max(ratio_cys, 1.0) # 1.4125 egfr_cr_cys = (135 * (min_cr2 ** alpha_cr2) * (max_cr2 ** -0.544) * (min_cys ** -0.323) * (max_cys ** -0.778) * (0.9961 ** age)) print(f"=== CKD-EPI 2021 Creatinine + Cystatin C Combined ===") print(f" Scr/κ = {ratio_cr2:.4f}") print(f" min(Scr/κ,1)^α = {min_cr2}^{alpha_cr2} = {min_cr2**alpha_cr2:.6f}") print(f" max(Scr/κ,1)^-0.544= {max_cr2:.4f}^-0.544 = {max_cr2**-0.544:.6f}") print(f" Scys/0.8 = {ratio_cys:.4f}") print(f" min(Scys/0.8,1)^-0.323 = {min_cys}^-0.323 = {min_cys**-0.323:.6f}") print(f" max(Scys/0.8,1)^-0.778 = {max_cys:.4f}^-0.778 = {max_cys**-0.778:.6f}") print(f" 0.9961^{age} = {0.9961**age:.6f}") print(f" eGFR (cr+cys) = {egfr_cr_cys:.2f} mL/min/1.73m²") # ─── 3. CKD-EPI 2012 Cystatin C-Only equation (for reference) ──────────────── # eGFR = 133 × min(Scys/0.8,1)^-0.499 × max(Scys/0.8,1)^-1.328 × 0.996^Age [× 0.932 if female] egfr_cys = (133 * (min_cys ** -0.499) * (max_cys ** -1.328) * (0.996 ** age)) print(f"\n=== CKD-EPI 2012 Cystatin C-Only (reference) ===") print(f" eGFR (cys only) = {egfr_cys:.2f} mL/min/1.73m²") # ─── CKD stage interpretation ──────────────────────────────────────────────── def ckd_stage(egfr): if egfr >= 90: return "G1 (normal or high)" elif egfr >= 60: return "G2 (mildly decreased)" elif egfr >= 45: return "G3a (mildly-moderately decreased)" elif egfr >= 30: return "G3b (moderately-severely decreased)" elif egfr >= 15: return "G4 (severely decreased)" else: return "G5 (kidney failure)" print(f"\n─── CKD Stage Classification ───") print(f" eGFR cr-only {egfr_cr:.1f} → CKD {ckd_stage(egfr_cr)}") print(f" eGFR cr+cys {egfr_cr_cys:.1f} → CKD {ckd_stage(egfr_cr_cys)}") print(f" eGFR cys-only {egfr_cys:.1f} → CKD {ckd_stage(egfr_cys)}") EOF