CPT code 84481: Free T3, unbound T3 measurement2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures unbound T3 in blood to assess thyroid function, especially during evaluation of thyrotoxicosis or other findings suggesting excess thyroid hormone.
Medicare pays $16.94 for 84481 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
$16.94
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 84481 covers
This laboratory test measures free triiodothyronine (T3), the portion of T3 circulating unbound to proteins. It is commonly ordered during evaluation of suspected hyperthyroidism or thyrotoxicosis, including when symptoms or other thyroid results suggest excess thyroid hormone. Clinicians may request it with thyroid-stimulating hormone (TSH) and free thyroxine (T4) to assess thyroid function. A clinical laboratory generally performs the test on a blood specimen.
Report this code for the free T3 measurement, distinguishing it from total T3 testing. Medicare pays the test under the CLFS, with one national amount applying in every locality and no office or facility payment difference. The 2026 national CLFS amount is $16.94, unchanged since 2020. The test is excluded from the physician fee schedule and is paid only through the CLFS.
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 84481
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 84481. 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 84481 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84481 on the lab fee schedule since 2020
84481 · CLFS 2026 Q4 (current)
$16.94
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.
84481 compared with similar tests
- 84480Total T3Total hormone measurement$14.18
- 84481 measures free T3; 84480 measures total T3, including protein-bound hormone.
- 84439Free T4Unbound thyroxine$9.02
- 84481 measures free triiodothyronine (T3), while 84439 measures free thyroxine (T4).
- 84443TSH testThyroid-stimulating hormone$16.80
- 84481 measures free T3 hormone; 84443 measures thyroid-stimulating hormone, a pituitary signal used to assess thyroid function.
- 84482Reverse T3Reverse triiodothyronine$15.76
- 84481 measures free T3; 84482 measures reverse T3, a different T3 form.
84481 billing questions
When should this code be used instead of 84480?
Use this code for a free T3 measurement. Code 84480 is for total T3, which measures both protein-bound and unbound T3.
Can this test be reported with TSH or free T4?
Free T3 may be ordered with TSH (84443) and free T4 (84439) as part of a thyroid evaluation.
Is a physician interpretation paid separately under this code?
Medicare pays 84481 only through the CLFS, not as a physician-fee-schedule service.
What should the claim represent?
Report the free T3 assay performed. Do not use this code to represent a total T3 measurement.
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
Fee sheets
Put 84481 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Build my fee sheet