CPT code 84479: Thyroid uptake, uptake or binding ratio2026 Medicare lab fee · Clinical Laboratory Fee Schedule
The thyroid hormone uptake assay evaluates serum binding-site availability and is reported when a laboratory performs an uptake or binding-ratio test.
Medicare pays $6.47 for 84479 under the 2026 Clinical Laboratory Fee Schedule: one national amount, the same in every state and setting.
Medicare lab fee · CLFS 2026 Q4
National CLFS amount
$6.47
In effect since Jan 1, 2026. The same amount in every state, payment locality and setting.
- Geographic adjustment
- None
- Office vs facility
- Same
- Since 2020
- Unchanged
- CMS updates
- Quarterly
Medicare pays the lesser of the lab’s charge and this amount. Patients usually owe no Part B deductible or coinsurance for covered clinical lab tests.
On this page 8 sections
What 84479 covers
Code 84479 identifies an indirect thyroid hormone uptake or binding-ratio assay. The serum test estimates the availability of binding sites for thyroid hormones; it does not measure a circulating T3 or T4 concentration. Clinicians may interpret the result with total T4 to derive a free thyroxine index during thyroid evaluation. Report this code when the uptake or binding-ratio assay is performed, rather than for a direct total or free hormone assay.
Medicare pays 84479 only under the Clinical Laboratory Fee Schedule (CLFS). The 2026 national CLFS amount is $6.47, unchanged since 2020. One amount applies in every state and locality, with no geographic adjustment or office-versus-facility difference. The code is excluded from the physician fee schedule.
This summary was written with AI assistance from CMS Clinical Laboratory Fee Schedule data. Amounts on this page come directly from CMS files.
How Medicare pays 84479
Clinical lab tests aren’t priced like physician services. They’re paid from their own fee schedule, with its own rules. See the whole lab fee schedule.
One national amount
CMS sets a single Clinical Laboratory Fee Schedule amount for 84479. There’s no geographic (GPCI) adjustment, so it pays the same in every state and payment locality.
No office or facility rate
Lab tests aren’t built from relative value units, so there’s no office and facility split: the place of service doesn’t change the CLFS amount.
Updated every quarter
CMS republishes the CLFS each quarter. New tests, often proprietary laboratory analyses (PLA codes), join during the year; existing amounts are updated each January.
Excluded from the physician fee schedule
The physician fee schedule lists 84479 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84479 on the lab fee schedule since 2020
84479 · CLFS 2026 Q4 (current)
$6.47
Unchanged since Jan 1, 2020
27 quarterly CLFS releases on file, first CLFS 2020 Q1. A code missing from a quarter wasn’t on that release.
84479 compared with similar tests
- 84436Total T4Total thyroxine$6.87
- 84436 measures total thyroxine. Choose 84479 for an uptake or binding-ratio assay; both may be performed together.
- 84439Free T4Unbound thyroxine$9.02
- 84439 measures free thyroxine directly, while 84479 reports an uptake or binding ratio. Code the assay performed.
- 84480Total T3Total hormone measurement$14.18
- 84480 measures triiodothyronine, while 84479 reports thyroid hormone uptake or binding ratio rather than a T3 concentration.
- 84443TSH testThyroid-stimulating hormone$16.80
- 84443 measures thyroid-stimulating hormone, a different test from the uptake or binding-ratio assay reported with 84479.
84479 billing questions
Does 84479 measure the amount of T3 in the blood?
No. It reports an uptake or binding-ratio result, not a T3 concentration.
When may 84479 be reported with total T4?
The uptake result may be interpreted with a total T4 result to calculate a free thyroxine index. Report 84479 and 84436 when both assays are performed.
How does 84479 differ from free T4 code 84439?
84479 reports thyroid hormone uptake or binding ratio; 84439 measures free thyroxine directly. Select the code that matches the assay performed.
Is a physician interpretation separately reported with 84479?
Medicare pays 84479 only under the CLFS; the code is excluded from the physician fee schedule.
Does Medicare use a different CLFS amount by location or setting?
No. One national amount applies across localities, with no office-versus-facility difference.
Where this amount comes from
FeeBase reads lab amounts directly from the CMS Clinical Laboratory Fee Schedule file for the quarter: one row per code, with its payment indicator and national amount. Contractor-priced tests are labeled, never given a made-up amount. Amounts are Medicare payment limits, not a patient’s bill or a commercial rate.
CMS CLFS 2026 Q4 · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file line behind this amount
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