CPT code 0665U: MASH biomarker, serum algorithm score2026 Medicare lab fee · Clinical Laboratory Fee Schedule
A serum biomarker algorithm combines YKL40 and miR-34a-5p testing to report a single score for metabolic dysfunction-associated steatohepatitis activity and fibrosis.
Medicare has no national amount for 0665U: it’s on the 2026 Clinical Laboratory Fee Schedule as contractor-priced, so each Medicare Administrative Contractor sets the payment.
Medicare lab fee · CLFS 2026 Q4
Contractor-priced (CLFS indicator L)
Set by your MAC
CMS lists 0665U on the Clinical Laboratory Fee Schedule without a national amount: each Medicare Administrative Contractor prices it for its jurisdiction.
- National amount
- None
- Priced by
- Each MAC
- Fee schedule
- Clinical lab
- CMS updates
- Quarterly
The contractor that processes the claim sets the amount for its jurisdiction. Patients usually owe no Part B deductible or coinsurance for covered clinical lab tests.
On this page 7 sections
What 0665U covers
This proprietary laboratory analysis uses serum to measure YKL40 by enzyme-linked immunosorbent assay and miR-34a-5p by quantitative reverse-transcription PCR. An algorithm combines the results into one score addressing metabolic dysfunction-associated steatohepatitis (MASH) activity and fibrosis. Its combined method pairs a protein assay with a microRNA assay to produce one reported result. The laboratory reports the algorithm’s single score; the code describes the combined analysis rather than separate reporting of its component measurements.
Report 0665U for the described serum analysis and algorithm result. The code was added to the Clinical Laboratory Fee Schedule effective October 1, 2026. Medicare pays it through the CLFS; it is locally priced, so each Medicare Administrative Contractor sets the payment. The code has no physician fee schedule row and 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 0665U
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.
Priced by each contractor
0665U carries CLFS indicator L: CMS publishes no national amount, and each Medicare Administrative Contractor sets the payment for its jurisdiction. Ask your MAC for its current amount.
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.
Not on the physician fee schedule
The physician fee schedule doesn’t list 0665U: Medicare pays the test only from the CLFS.
0665U compared with similar tests
- 91200Liver elastographyTransient shear-wave method$29.69–$45.82
- 0665U combines serum biomarkers into a score for MASH activity and fibrosis. Code 91200 describes liver elastography, which assesses liver stiffness by a different method.
- 47000Liver biopsyPercutaneous needle$252.95–$392.18
- 0665U is a serum laboratory analysis. Code 47000 describes a percutaneous liver biopsy, which obtains tissue for examination.
- 81596HCV fibrosis testSix-assay serum algorithm$72.19
- 81596 is a serum algorithm for liver fibrosis and necroinflammatory activity; 0665U combines YKL40 and miR-34a-5p results into a score for MASH activity and fibrosis.
0665U billing questions
What specimen and methods identify this test?
The analysis uses serum, measuring YKL40 by ELISA and miR-34a-5p by quantitative reverse-transcription PCR. The results feed an algorithm that reports one score.
What does the reported score address?
The score addresses MASH activity and fibrosis. It combines the assay results rather than reporting each as a separate scored test.
Is this the same as liver elastography?
No. This code describes a serum biomarker algorithm; liver elastography assesses liver stiffness using a different method.
Is a physician interpretation billed separately?
0665U has no physician fee schedule row and is paid only from the CLFS.
How does Medicare pay this code?
The code is locally priced under the CLFS. Each Medicare Administrative Contractor sets the payment.
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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