# CPT 84479

> Not at a published national rate. CPT 84479 carries status X (statutory exclusion) in the Q3 2024 release. The statutory definition of physician services does not include this item. Treat the blank amount as unpriced, not as $0.

## What it is

An older thyroid lab method that estimates how many binding sites on the blood's carrier proteins are already taken up by thyroid hormone. It does not report a hormone level directly - instead the result is combined with a total T4 measurement to calculate an index that approximates free hormone. Direct free-hormone assays have largely displaced this approach, though the test still appears in some panels and older ordering habits.

## Selected release

- Release: Q3 2024 (2024 C)
- Effective: July 1 – September 30, 2024
- Status indicator: X
- Office (non-facility) national allowed amount: not published
- Facility national allowed amount: not published
- Sequestration: not applied

## RVUs and formula

- Work RVU: not published
- Office (non-facility) practice expense RVU: not published
- Facility practice expense RVU: not published
- Malpractice RVU: not published
- Conversion factor: 33.2875
- Formula: `(work_rvu × work_gpci + pe_rvu × pe_gpci + mp_rvu × mp_gpci) × conversion_factor`

## Source and citation

- Source: Physician relative value file (Q3 2024)
- CMS file: https://www.cms.gov/files/zip/rvu24c-updated-09/09/2024.zip
- Parsed file: PPRRVU24_JUL.csv, row 15,988
- Canonical page: https://localishealth.com/cpt/84479/2014/B
- Release-specific citation URL: https://localishealth.com/cpt/84479/2024/C
- Last significant update: 2026-08-04T03:14:09+00:00