Source: https://guthlabs.ai/docs/instruments/bilirubin-jaundice-risk-reference-education/mechanism/

instrument mechanism / verified-clean

# Bilirubin/Jaundice Risk Reference (education) mechanism

The inspectable method record for Bilirubin/Jaundice Risk Reference (education), kept separate from implementation and qualification.

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

## Model scope

NEEDS_REVIEW because the canonical curve dataset, interpolation method, validated age and gestational-age scope, unit contract, and mapping from Bhutani's four zones to the requested three labels are not specified. The existing educational-only disclaimer is appropriate but should explicitly state that the display is not a diagnostic tool and not a phototherapy or exchange-transfusion threshold.

- The Bhutani nomogram is a lookup against percentile curves, but the specification does not provide the actual curve table or define whether age interpolation is linear, spline-based, or nearest-row lookup.

- The Bhutani nomogram conventionally distinguishes four zones: low-risk (<40th percentile), low-intermediate-risk (40th–75th), high-intermediate-risk (75th–95th), and high-risk (>95th). The stated three outputs—low/intermediate/high—do not define how the four zones are collapsed.

- Boundary behavior is unspecified. In the vectors below, the educational mapping assumes low = below the 40th percentile, intermediate = 40th through 95th percentile inclusive, and high = above the 95th percentile.

- The nomogram is not a treatment-threshold calculator and must not be used to determine phototherapy or exchange-transfusion treatment.

- Applicability constraints are missing: the classic Bhutani nomogram is generally used for infants at or above 35 weeks' gestation, during its validated postnatal-age range, commonly approximately 18–144 hours. Gestational age and clinical context are absent inputs.

- The specification does not distinguish total serum bilirubin from transcutaneous bilirubin, direct bilirubin, or indirect bilirubin.

## Units and conventions

- Bilirubin values in the reference table are total serum bilirubin in mg/dL.

- For the conversion-trap vector, 1 mg/dL is treated as 17.1 micromol/L; therefore 171 micromol/L = 10.0 mg/dL.

- Age is postnatal age in completed hours, not gestational age or day-of-life rounded to 24-hour blocks.

- The test vectors use commonly reproduced, rounded Bhutani nomogram anchor values. A production implementation requires a validated, explicitly sourced digitization of the chosen Bhutani curve.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "age_hours": 24,
    "total_serum_bilirubin_mg_dL": 5
  },
  "expected_outputs": {
    "percentile_zone": "intermediate",
    "boundary_interpretation": "exactly at 40th percentile"
  },
  "reference_data": {
    "age_24_hours": {
      "5th_percentile_mg_dL": 3,
      "40th_percentile_mg_dL": 5,
      "75th_percentile_mg_dL": 6,
      "95th_percentile_mg_dL": 8,
      "source_convention": "Bhutani et al., Pediatrics 1999, commonly reproduced rounded nomogram anchor values"
    }
  },
  "working": "At 24 hours, the 40th-percentile boundary is 5.0 mg/dL. Input = 5.0 mg/dL. 5.0 >= 5.0, so it is not low. It is also 5.0 <= 8.0, the 95th-percentile boundary. Under the stated boundary convention, the result is intermediate."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The instrument is specified as a lookup-table tool, but the required Bhutani nomogram data points, validity interval, interpolation policy, risk-zone thresholds, and input units are not supplied. It therefore cannot produce a defensible percentile zone for ordinary or boundary inputs and must reject or explicitly flag them rather than inventing results.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/bilirubin-jaundice-risk-reference-education/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/bilirubin-jaundice-risk-reference-education/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/bilirubin-jaundice-risk-reference-education/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-tranche7/tranche7-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`