CPT code 81121: IDH2 Testing, common variants2026 Medicare lab fee · Clinical Laboratory Fee Schedule
IDH2 common-variant analysis tests for variants such as R140W and R172M and supports focused molecular characterization, including glioma workups.
Medicare pays $295.79 for 81121 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
$295.79
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 81121 covers
IDH2 common-variant analysis examines the isocitrate dehydrogenase 2 gene for variants such as R140W and R172M. The result can contribute to molecular characterization of glioma. This is a focused test for common variants, distinct from full-gene sequencing. Molecular pathology laboratories perform and report the assay in tumor testing; the code identifies testing of IDH2 rather than an individual variant.
Code 81121 reports the IDH2 common-variant assay. Medicare pays it only through the CLFS, at one national amount that applies across localities and in office and facility settings. The 2026 national CLFS amount is $295.79, unchanged since 2020. The physician fee schedule excludes this test; Medicare 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 81121
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 81121. 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 81121 with status X (excluded by statute), so the test itself is paid only from the CLFS.
81121 on the lab fee schedule since 2020
81121 · CLFS 2026 Q4 (current)
$295.79
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.
81121 compared with similar tests
- 81120IDH1 testingCommon variants$193.25
- 81120 analyzes common IDH1 variants; 81121 analyzes common IDH2 variants. The gene tested determines the code.
- 81450Hematolymphoid panel5–50 genes, DNA or combined$759.53
- 81450 represents a multigene panel for hematologic neoplasms or disorders. Use 81121 for focused IDH2 common-variant testing rather than panel testing.
- 81455Tumor genomic panel51+ genes, DNA or DNA/RNA$2,919.60
- 81455 represents a broader sequencing panel for solid-organ tumors. Code 81121 describes focused testing of common IDH2 variants.
81121 billing questions
How does this differ from IDH1 testing?
This code covers common variants in IDH2. Code 81120 covers common IDH1 variants; select the code for the gene analyzed.
Does this represent full IDH2 gene sequencing?
No. It describes focused analysis for common IDH2 variants, not full-gene sequencing.
Is a physician interpretation separately payable?
Medicare pays this test only through the CLFS. The physician fee schedule excludes the test.
Does payment vary by locality or setting?
No. The CLFS amount is national and applies across localities, with no office-versus-facility difference.
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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