CPT code 81538: Lung survival assay, serum protein signature2026 Medicare lab fee · Clinical Laboratory Fee Schedule
This serum-based mass spectrometry test analyzes an eight-protein lung tumor signature to classify predicted overall survival as good or poor.
Medicare pays $2,871.00 for 81538 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
$2,871.00
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 81538 covers
This assay uses mass spectrometry to analyze serum for an eight-protein lung tumor signature that includes amyloid A. An algorithm uses the signature to predict overall survival and classifies the result as good or poor. The test supports prognostic and predictive assessment of lung tumor cells; it analyzes serum rather than a lung tumor tissue specimen.
For Medicare claims, report CPT 81538 for this serum-based lung oncology assay. Medicare pays the test only through the CLFS, at one national amount applicable in every state and locality, with no geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $2,871.00, unchanged from 2020 through 2026. The reported category is good or poor overall survival. The test 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 81538
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 81538. 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 81538 with status X (excluded by statute), so the test itself is paid only from the CLFS.
81538 on the lab fee schedule since 2020
81538 · CLFS 2026 Q4 (current)
$2,871.00
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.
81538 compared with similar tests
- 81539Prostate risk scoreFour-protein probability score$760.00
- 81539 is an oncology assay focused on prostate cancer. 81538 is the serum protein assay for lung tumor survival classification.
- 81540Tumor classifier92-gene mRNA assay$3,750.00
- 81540 is for an oncology assay addressing a tumor of unknown origin. 81538 evaluates predicted survival using a lung tumor serum protein signature.
- 81554IPF gene test190-gene mRNA algorithm$5,409.60
- 81554 is a molecular assay for idiopathic pulmonary fibrosis, not a lung oncology survival assay.
81538 billing questions
What specimen does this assay use?
It uses serum to analyze the eight-protein signature, which includes amyloid A. The assay is not performed on a lung tumor tissue specimen.
What does the assay report?
An algorithm classifies predicted overall survival as good or poor.
How is 81538 different from 81540?
81538 is a lung oncology assay that predicts overall survival from a serum protein signature. 81540 is an oncology assay for tumors of unknown origin.
How does Medicare pay for 81538?
Medicare pays it through the CLFS at one national amount that applies across states and localities, without geographic or office-versus-facility adjustments. The test is excluded from the physician fee schedule.
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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