CPT code 84437: Neonatal T4, elution-based assay2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Reports thyroxine measured after elution, typically in neonatal screening when an eluted blood-spot specimen is tested for possible thyroid disease.
Medicare pays $6.47 for 84437 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 84437 covers
CPT 84437 reports a thyroxine (T4) assay performed after elution, a format associated with neonatal testing. Newborn-screening laboratories commonly test eluted blood-spot specimens collected on filter paper to screen for thyroid disorders such as congenital hypothyroidism. An abnormal screening result can prompt clinical assessment and follow-up testing. This assay is distinct from total or free T4 testing reported under other codes.
Medicare pays 84437 only through the Clinical Laboratory Fee Schedule (CLFS). The 2026 national amount is $6.47, unchanged from 2020 through 2026. The same CLFS amount applies across states and localities, with no geographic or office-versus-facility adjustment. The test is paid only from 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 84437
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 84437. 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 84437 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84437 on the lab fee schedule since 2020
84437 · 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.
84437 compared with similar tests
- 84436Total T4Total thyroxine$6.87
- 84437 is for thyroxine testing requiring elution, commonly in neonatal screening. Code 84436 reports total thyroxine testing.
- 84439Free T4Unbound thyroxine$9.02
- 84439 measures free thyroxine. Code 84437 reports an elution-based neonatal thyroxine assay.
- 84443TSH testThyroid-stimulating hormone$16.80
- 84443 measures thyroid-stimulating hormone, not thyroxine. It may be performed as a separate analyte in newborn screening.
- 84479Thyroid uptakeUptake or binding ratio$6.47
- 84479 reports a thyroid hormone uptake or binding-ratio assay, not an elution-based neonatal thyroxine measurement.
84437 billing questions
What specimen is associated with 84437?
It is associated with an eluted neonatal specimen, commonly a dried blood spot collected on filter paper.
When should 84437 be reported instead of 84436?
Use 84437 for the thyroxine assay requiring elution. Code 84436 is for total thyroxine testing.
Is 84437 used for free T4 testing?
No. It reports an elution-based neonatal thyroxine assay; free thyroxine testing is reported with 84439.
How does Medicare pay for 84437?
Medicare pays it through the CLFS at one national amount across localities and settings. The test is paid only from the CLFS.
Can 84437 be reported with a TSH assay?
Newborn-screening approaches may include both T4 and TSH testing. Code 84443 reports the TSH assay when it is also performed.
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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