CPT code 84445: TSI assay, stimulating thyroid antibodies2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures thyroid-stimulating immunoglobulins, typically to support evaluation of Graves disease and clarify the cause of excess thyroid activity.
Medicare pays $50.86 for 84445 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
$50.86
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 84445 covers
This laboratory test measures thyroid-stimulating immunoglobulins, autoantibodies that can activate the thyroid. Clinicians commonly order it when evaluating suspected Graves disease or clarifying the cause of hyperthyroidism. The result can help distinguish antibody-driven thyroid stimulation from other causes of abnormal thyroid function. A clinical laboratory performs and reports the assay; the ordering clinician interprets the result alongside the patient’s symptoms and other thyroid testing.
Report 84445 for the TSI assay; it represents the assay alone, not a panel of thyroid tests. Medicare pays it only through the CLFS, at one national amount in every state and locality, with no office-versus-facility difference. The 2026 national CLFS amount is $50.86, unchanged from 2020 through 2026. The test 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 84445
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 84445. 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 84445 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84445 on the lab fee schedule since 2020
84445 · CLFS 2026 Q4 (current)
$50.86
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.
84445 compared with similar tests
- 84442TBG assayProtein level$14.78
- 84445 reports a TSI assay; 84442 reports a thyroid-stimulating activity assay. Use the code corresponding to the specific assay performed.
- 84443TSH testThyroid-stimulating hormone$16.80
- 84443 measures thyroid-stimulating hormone, while 84445 measures stimulating thyroid immunoglobulins. They assess different substances and are not interchangeable.
- 84439Free T4Unbound thyroxine$9.02
- 84439 measures free thyroxine, a thyroid hormone. Code 84445 measures thyroid-stimulating immunoglobulins, an antibody test.
84445 billing questions
When should 84445 be reported instead of 84443?
Report 84445 for a thyroid-stimulating immunoglobulin assay. Code 84443 measures thyroid-stimulating hormone, a different test used to assess thyroid function.
How does 84445 differ from 84442?
84445 identifies the TSI assay. Code 84442 represents a thyroid-stimulating activity assay; select the code that matches the test performed and reported.
Is 84445 a panel or does it include thyroid hormone tests?
No. It reports the TSI assay alone; tests such as TSH or free thyroxine are separate assays when ordered and performed.
What documentation supports reporting 84445?
The laboratory record should identify the TSI assay performed and reported. The ordering clinician interprets the result alongside the clinical presentation and other thyroid testing.
How does Medicare pay for 84445?
Medicare pays the test through the CLFS using one national amount across localities, without an office-versus-facility difference. It is excluded from the physician fee schedule.
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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