CPT code 81120: IDH1 testing, common variants2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Targeted IDH1 gene analysis identifies common variants and is reported in molecular evaluation of tumors, particularly gliomas.
Medicare pays $193.25 for 81120 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
$193.25
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 81120 covers
Molecular pathology laboratories analyze IDH1 for common variants, including changes such as R132H and R132C. The test is used in tumor characterization, particularly in glioma evaluation, where IDH1 findings contribute to classification. The laboratory reports the molecular result for clinical interpretation alongside other diagnostic findings.
Report 81120 for the IDH1 common-variant analysis; the code represents the analysis rather than a separate unit for each variant examined. Medicare pays the test only through the CLFS. The 2026 national amount is $193.25 and is the same in every locality, without an office-versus-facility adjustment; that amount has remained unchanged since 2020. The code 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 81120
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 81120. 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 81120 with status X (excluded by statute), so the test itself is paid only from the CLFS.
81120 on the lab fee schedule since 2020
81120 · CLFS 2026 Q4 (current)
$193.25
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.
81120 compared with similar tests
- 81121IDH2 TestingCommon variants$295.79
- Choose 81120 for IDH1 common-variant analysis and 81121 for IDH2 common-variant analysis; the genes are distinct.
- 88342Antibody stainFirst single antibody per specimen$97.65–$150.80
- 88342 reports an immunohistochemical stain, such as an IDH1 R132H stain. Code 81120 reports molecular analysis of common IDH1 variants.
81120 billing questions
How does this differ from IDH2 testing?
This code is for common variants in IDH1. Use 81121 when the analysis is for IDH2.
Is this the same as IDH1 immunohistochemistry?
No. Code 81120 reports molecular analysis; 88342 reports an immunohistochemical stain, such as an IDH1 R132H stain.
Are units reported for each variant tested?
No. The code represents analysis of common IDH1 variants, not a separate service for each variant.
How does Medicare pay for this test?
Medicare pays it through the CLFS at one national amount, with no locality or office-versus-facility adjustment.
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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