Source: https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/mechanism/

instrument mechanism / verified-clean

# eGFR (MDRD, legacy) mechanism

The inspectable method record for eGFR (MDRD, legacy), kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

Educational estimate only and not medical advice, consistent with the supplied honest label. The catalog must explicitly identify whether this is the race-free IDMS-traceable MDRD variant with coefficient 175, rather than another historical MDRD variant.

- The formula is correct for the IDMS-traceable 4-variable MDRD equation without a race coefficient: 175×SCr^-1.154×Age^-0.203×(0.742 if female). However, 'MDRD, legacy' is ambiguous because historical MDRD variants commonly used a 186 coefficient and, in older implementations, an additional Black race coefficient; the intended variant must be named explicitly.

- The input 'sex' is underspecified: the formula defines a female multiplier, but behavior for unknown, nonbinary, or missing values is not stated.

## Units and conventions

- Age is in completed years and serum creatinine is in mg/dL.

- The output is normalized to a body-surface area of 1.73 m² and is reported in mL/min/1.73 m².

- If serum creatinine is supplied in µmol/L, convert using SCr_mg/dL = SCr_µmol/L ÷ 88.4 before applying the formula.

- The 0.742 multiplier applies only when the selected formula convention classifies the patient as female; otherwise the multiplier is 1.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "age_years": 60,
    "sex": "male",
    "serum_creatinine_mg_dL": 1
  },
  "expected_outputs": {
    "eGFR_mL_min_1_73m2": 76.22
  },
  "working": "SCr^-1.154 = 1.0^-1.154 = 1.000. Age^-0.203 = 60^-0.203 ≈ 0.43555. Male multiplier = 1.000. eGFR = 175 × 1.000 × 0.43555 × 1.000 = 76.22 mL/min/1.73 m²."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The formula has undefined or non-physiologic boundary inputs that require validation: age = 0 produces an infinite mathematical result, negative serum creatinine produces an undefined real power, and an unspecified creatinine unit can produce an orders-of-magnitude error.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/qualification/>)

## 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`