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

instrument implementation / implementation-contract

# eGFR (MDRD, legacy) implementation

A source-bound implementation contract for eGFR (MDRD, legacy); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-026

**Effect**: Computation or source lookup only

## Input and validation requirements

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.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "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."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/egfr-mdrd-legacy/mechanism/>)[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`