CPT code 80184: Phenobarbital level, quantitative drug assay2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures phenobarbital concentration to support therapeutic drug monitoring during anticonvulsant treatment, including dose assessment or evaluation of suspected toxicity.
Medicare pays $15.30 for 80184 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
$15.30
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 7 sections
What 80184 covers
This laboratory assay measures phenobarbital concentration in a blood specimen, typically serum, for patients receiving phenobarbital therapy. Neurologists and other clinicians may order it to monitor drug exposure, assess a response to treatment, guide dose decisions, or evaluate a suspected adverse effect or toxicity. Hospital and independent laboratories perform the assay for outpatient and facility patients.
Report 80184 for the phenobarbital assay performed; it represents measurement of this drug, not a broader anticonvulsant panel. Medicare pays the test under the CLFS at one national amount that applies in every state and locality, with no office-versus-facility payment difference. The 2026 national CLFS amount is $15.30, unchanged since 2020. 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 80184
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 80184. 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 80184 with status X (excluded by statute), so the test itself is paid only from the CLFS.
80184 on the lab fee schedule since 2020
80184 · CLFS 2026 Q4 (current)
$15.30
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.
80184 compared with similar tests
- 80185Phenytoin levelTotal drug concentration$13.25
- 80185 measures total phenytoin, not phenobarbital. Select the code for the drug whose concentration the laboratory measured.
- 80186Phenytoin levelUnbound concentration$13.76
- 80186 measures free phenytoin. It is distinct from both total phenytoin testing and phenobarbital measurement.
- 80188Primidone levelTherapeutic drug assay$16.59
- 80188 measures primidone. Use 80184 when the assay measures phenobarbital.
80184 billing questions
When should 80184 be chosen instead of a phenytoin assay?
Use 80184 when the measured drug is phenobarbital. Use 80185 for total phenytoin or 80186 for free phenytoin.
Does 80184 measure primidone as well as phenobarbital?
No. 80184 is the phenobarbital assay; 80188 is the separate primidone assay.
Does 80184 include a broader anticonvulsant panel?
No. It represents measurement of phenobarbital, not a broader anticonvulsant panel.
How does Medicare pay for 80184?
Medicare pays one national CLFS amount that applies across localities and in both office and facility settings. The test is paid only from the CLFS.
What should the order or documentation identify?
Documentation should support that phenobarbital concentration was measured, such as for treatment monitoring or evaluation of a suspected drug effect. Do not substitute a primidone or phenytoin assay code when a different drug was measured.
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 · Coming soon
Put 80184 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Join the waitlist