Source: https://guthlabs.ai/docs/instruments/creatinine-clearance-cockcroft-gault/mechanism/

instrument mechanism / verified-clean

# Creatinine Clearance (Cockcroft-Gault) mechanism

The inspectable method record for Creatinine Clearance (Cockcroft-Gault), kept separate from implementation and qualification.

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

## Model scope

NEEDS_REVIEW because the exact weight convention and the allowed/meaningful sex categories are ambiguous. The educational, not-medical-advice label is appropriate, but the interface should also explicitly distinguish estimated Cockcroft-Gault creatinine clearance from eGFR and enforce positive SCr, positive weight, and valid age constraints.

- The algebraic formula is the standard Cockcroft-Gault form when age is in years, weight is in kg, and serum creatinine is in mg/dL.

- The weight definition is unspecified: actual body weight, ideal body weight, or adjusted body weight may be selected clinically depending on body composition and institutional dosing policy.

- The sex adjustment is represented only as a binary 0.85 multiplier; the applicable sex category and handling of patients who do not fit that binary input are unspecified.

- The formula does not state an applicable age range or constraints for physiologically valid inputs.

## Units and conventions

- Age is measured in completed years.

- Weight is measured in kilograms.

- Serum creatinine (SCr) is measured in mg/dL; a value reported in µmol/L must be divided by 88.4 before use.

- The resulting CrCl is reported in mL/min without automatic normalization to body-surface area.

- The 0.85 multiplier is applied for female input and 1.00 otherwise, subject to the sex-category ambiguity noted above.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "age_years": 50,
    "weight_kg": 70,
    "sex": "male",
    "serum_creatinine_mg_dL": 1
  },
  "expected_outputs": {
    "creatinine_clearance_mL_min": 87.5
  },
  "working": "140 − 50 = 90; 90 × 70 = 6300; female factor = 1.00; denominator = 72 × 1.0 = 72; CrCl = 6300 ÷ 72 = 87.5 mL/min."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

A serum creatinine input of exactly zero produces division by zero, so the instrument must reject the input or return an explicit undefined result rather than a numeric clearance.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/creatinine-clearance-cockcroft-gault/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/creatinine-clearance-cockcroft-gault/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/creatinine-clearance-cockcroft-gault/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`