Source: https://guthlabs.ai/docs/instruments/body-surface-area-du-bois/

instrument / verified-with-binding-errata

# Body Surface Area (Du Bois)

The current ledger marks this instrument verified with errata that must be applied at binding time.

Status: **VERIFIED_WITH_ERRATA**Lifecycle: **verified-with-binding-errata**

## Inspectable records

[01**Overview**Purpose and lifecycle](<https://guthlabs.ai/docs/instruments/body-surface-area-du-bois/>)[02**Mechanism**Method and assumptions](<https://guthlabs.ai/docs/instruments/body-surface-area-du-bois/mechanism/>)[03**Implementation**Binding and validation](<https://guthlabs.ai/docs/instruments/body-surface-area-du-bois/implementation/>)[04**Qualification**Evidence and errata](<https://guthlabs.ai/docs/instruments/body-surface-area-du-bois/qualification/>)

## Ledger state

The current ledger marks this instrument verified with errata that must be applied at binding time.

**Area**: Biology, Medicine & Pharmacology

**Tranche**: tranche-2

**Evidence ID**: t2-002

**Ledger rows**: 1

No ledger note is attached.

## Review findings

Du Bois and Mosteller formulas are correct under the stated kg/cm conventions. Verdict is NEEDS_REVIEW because the specification promises Haycock support without supplying its formula and leaves formula-selection behavior ambiguous.

### Formula and scope findings

- The Du Bois formula BSA=0.007184·W^0.425·H^0.725 is standard when W is in kg and H is in cm.

- The Mosteller formula BSA=√(H·W/3600) is standard when H is in cm and W is in kg.

- ios27_notes claims a Haycock formula toggle, but no Haycock formula is provided for verification or implementation. The standard Haycock form is approximately BSA=0.024265·H^0.3964·W^0.5378 with H in cm and W in kg.

- The formula-select input does not specify a default, accepted selector values, or behavior when the selector is missing or invalid.

### Unit assumptions

- Weight W must be provided in kilograms.

- Height H must be provided in centimeters; using height in meters without conversion produces an incorrect result.

- The constant 3600 in the Mosteller formula is valid for kilograms and centimeters and yields BSA in square meters.

- Both inputs must be finite, nonnegative numeric values for mathematical evaluation; clinical use should require strictly positive values.

## Boundary hardening

**BREAK_CLAIMED** · SELF_FLAGGED

The instrument reaches undefined NaN-like results for negative inputs, accepts a mathematically zero but physically invalid weight unless validation is added, and is vulnerable to materially different BSA values when kg/cm versus lb/in conventions are not explicit.

## Errata and corrections

No applied erratum is attached to this unique-name record.

## Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

````
{
  "inputs": {
    "weight_kg": 70,
    "height_cm": 170,
    "formula_select": "Du Bois"
  },
  "expected_outputs": {
    "bsa_m2": 1.81
  },
  "working": "BSA=0.007184·70^0.425·170^0.725. 70^0.425≈6.0837. 170^0.725≈41.4071. 6.0837·41.4071≈251.907. 0.007184·251.907≈1.8097 m², which rounds to 1.810 m²."
}
````

## Related workflows

No source-defined multi-instrument workflow membership is recorded.

## Sources and evidence

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

- `VERIFIED_LEDGER.json · VERIFIED_WITH_ERRATA`

- `evidence-tranche2/tranche2-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`