CPT code 80168: Ethosuximide level2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures ethosuximide in a patient specimen to monitor drug levels during treatment, including evaluation of seizure control, possible adverse effects, or dose changes.
Medicare pays $16.34 for 80168 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
$16.34
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 80168 covers
This test measures the concentration of ethosuximide, an antiseizure medication commonly used to treat absence seizures. Clinicians may order it during treatment to help assess drug exposure when adjusting therapy, evaluating ongoing seizures or possible medication effects, or investigating adherence. A clinical laboratory performs the assay on a blood specimen; the result supports the treating clinician’s medication management.
Report 80168 for an ethosuximide assay rather than for a different antiseizure medication level. Medicare pays the test through the Clinical Laboratory Fee Schedule (CLFS). The 2026 national CLFS amount is $16.34, unchanged from 2020 through 2026. The amount is the same across states and localities, with no office-versus-facility difference. The physician fee schedule classifies the test as excluded by statute, so payment is 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 80168
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 80168. 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 80168 with status X (excluded by statute), so the test itself is paid only from the CLFS.
80168 on the lab fee schedule since 2020
80168 · CLFS 2026 Q4 (current)
$16.34
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.
80168 compared with similar tests
- 80164Valproate levelTotal concentration$13.54
- 80164 measures total valproic acid, not ethosuximide. Select based on which medication the laboratory is assaying.
- 80175Lamotrigine levelQuantitative drug assay$13.25
- 80175 measures lamotrigine. Use 80168 only for an ethosuximide assay.
- 80167Felbamate assayDrug concentration$18.64
- 80167 measures felbamate rather than ethosuximide; these codes are not interchangeable.
80168 billing questions
When should 80168 be selected instead of another antiseizure drug assay?
Select 80168 when the laboratory is measuring ethosuximide. Choose a different drug assay code when the medication being measured is another drug, such as valproic acid or lamotrigine.
Is 80168 selected based on the medication or the seizure type?
Select it based on the medication being measured: 80168 is for an ethosuximide assay.
Does Medicare pay 80168 under the physician fee schedule?
Medicare pays this test through the CLFS. The physician fee schedule classifies it as excluded by statute.
Does payment vary by locality or setting?
No. The CLFS amount is national and has no geographic adjustment or office-versus-facility difference.
What specimen is tested?
The assay is performed on a blood specimen.
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 80168 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Join the waitlist