CPT code 85385: Fibrinogen antigen, antigen, not activity2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures fibrinogen protein antigen to help characterize suspected fibrinogen disorders when protein quantity is compared with clot-forming activity.
Medicare pays $14.46 for 85385 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
$14.46
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 85385 covers
Fibrinogen antigen testing measures the amount of fibrinogen protein, also called factor I, rather than how well it functions in clot formation. Clinicians may use it when evaluating suspected inherited or acquired fibrinogen abnormalities. Coagulation laboratories typically perform the assay on plasma for hematologists and other clinicians investigating abnormal coagulation findings. Comparing antigen concentration with fibrinogen activity can help distinguish reduced protein quantity from impaired function.
Report 85385 for the antigen test performed; report 85384 separately when fibrinogen activity is also measured. Report one unit for each test performed; the measured concentration is not the unit count. Medicare pays 85385 through the CLFS, with one national amount in every locality and no office-versus-facility payment difference. The 2026 national CLFS amount is $14.46, unchanged since 2020. Payment is through the CLFS only.
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 85385
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 85385. 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 85385 with status X (excluded by statute), so the test itself is paid only from the CLFS.
85385 on the lab fee schedule since 2020
85385 · CLFS 2026 Q4 (current)
$14.46
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.
85385 compared with similar tests
- 85384Fibrinogen testFunctional activity$9.72
- Use 85385 for fibrinogen protein antigen quantity and 85384 for fibrinogen activity. Both may be performed when quantity and function are being compared.
- 85379D-dimerQuantitative assay$10.18
- 85379 measures fibrin-degradation products quantitatively, not fibrinogen protein antigen.
- 85380D-dimerQualitative or semiquantitative$10.18
- 85380 tests for D-dimer, a fibrin breakdown product; 85385 measures fibrinogen antigen.
85385 billing questions
How does 85385 differ from fibrinogen activity code 85384?
85385 measures the amount of fibrinogen protein. 85384 measures its clot-forming activity; both may be performed to compare quantity with function.
Can antigen and activity testing both be reported?
Yes, when both distinct tests are performed. Report 85385 for antigen testing and 85384 for activity testing.
What unit should be reported?
Report one unit for each antigen test performed. Do not use multiple units to represent the measured fibrinogen concentration.
How does Medicare pay for 85385?
Medicare pays 85385 under the CLFS at one national amount, without locality or office-versus-facility variation.
What should the record support?
Documentation should identify the fibrinogen antigen test performed and the clinical reason for measuring fibrinogen protein.
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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