eGFR (CKD-EPI 2021, race-free) mechanism

Model scope

The canonical equation and test vectors above are based on CKD-EPI 2021 creatinine-only, race-free constants. Because the supplied formulas field contains only a description and not the equation itself, the implementation remains NEEDS_REVIEW until the exact equation, supported age range, sex-input policy, validation rules, and KDIGO labeling semantics are explicitly specified.

• The specification names the CKD-EPI 2021 creatinine equation but does not provide its actual constants, exponents, piecewise min/max terms, or sex-specific k and alpha values, so the implementation cannot be verified from the spec alone.
• The standard equation estimates eGFR for adults and requires explicit handling of the valid age domain, generally age >=18 years.
• The output label 'CKD stage' is potentially misleading: eGFR categories G1-G5 are not, by themselves, a CKD diagnosis; CKD requires appropriate chronicity and/or other markers of kidney damage.

Units and conventions

• Serum creatinine (SCr) is entered in mg/dL. If supplied in µmol/L, convert using SCr_mg/dL = SCr_µmol/L / 88.4 before applying the equation.
• Age is in completed years.
• The canonical 2021 race-free CKD-EPI creatinine equation is assumed: eGFR = 142 × min(SCr/k,1)^alpha × max(SCr/k,1)^(-1.200) × 0.9938^Age × 1.012 if female; k = 0.7 and alpha = -0.241 for female, k = 0.9 and alpha = -0.302 for male.
• Sex is assumed to be the binary equation parameter male or female; the spec does not define handling for intersex, nonbinary, or unknown sex inputs.
• eGFR output is in mL/min/1.73 m².
• KDIGO eGFR categories are assumed to be G1 >=90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, and G5 <15 mL/min/1.73 m².

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "age_years": 40,
    "sex": "male",
    "serum_creatinine_mg_dL": 0.9
  },
  "expected_outputs": {
    "eGFR_mL_min_1_73m2": 110.73,
    "stage_label": "G1"
  },
  "working": "Male: k = 0.9, alpha = -0.302. SCr/k = 0.9/0.9 = 1. Therefore min(1,1)^(-0.302) = 1 and max(1,1)^(-1.200) = 1. Age factor = 0.9938^40 = 0.77976. eGFR = 142 × 1 × 1 × 0.77976 = 110.73 mL/min/1.73 m². Since 110.73 >= 90, the eGFR category is G1."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A serum creatinine input of exactly 0 causes the negative power 0^(-0.302), producing an undefined or non-finite result. The instrument should reject this input instead of assigning an eGFR or CKD stage.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json