CPT code 86638: Q fever antibody, coxiella burnetii antibody2026 Medicare lab fee · Clinical Laboratory Fee Schedule
This laboratory antibody analysis measures the immune response to Coxiella burnetii and is reported for testing directed at Q fever.
Medicare pays $12.12 for 86638 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
$12.12
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 86638 covers
Code 86638 represents laboratory analysis for antibodies to Coxiella burnetii, the bacterium associated with Q fever. It identifies the target of the antibody analysis, rather than a general infectious-disease or fever evaluation. Clinical laboratories report the code when the performed analysis is directed at antibodies to this organism.
Medicare pays this test under the CLFS, with one national amount per code in every state and locality and no geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $12.12, unchanged from 2020 through 2026. The test is excluded from the physician fee schedule and is paid only through the CLFS. Report 86638 for the Q fever antibody analysis; payment follows the CLFS amount for the code.
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 86638
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 86638. 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 86638 with status X (excluded by statute), so the test itself is paid only from the CLFS.
86638 on the lab fee schedule since 2020
86638 · CLFS 2026 Q4 (current)
$12.12
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.
86638 compared with similar tests
- 86622Brucella antibodyBrucella-specific serology$8.93
- Use 86638 for antibodies to Coxiella burnetii; use 86622 when the antibody analysis targets Brucella.
- 86635Coccidioides antibodySerologic test$11.47
- 86638 represents antibody analysis for Coxiella burnetii, while 86635 represents antibody analysis for Coccidioides.
- 86618Lyme antibodyLyme disease antibody$17.03
- 86618 is for Lyme disease antibody testing. 86638 is directed at antibodies to Coxiella burnetii.
86638 billing questions
What does 86638 test?
It represents an antibody analysis directed at Coxiella burnetii, the bacterium associated with Q fever.
How does 86638 differ from the Brucella antibody code?
86638 is for antibodies to Coxiella burnetii; 86622 is for antibodies to Brucella. Select the code matching the organism targeted by the analysis.
Does Medicare pay this test under the physician fee schedule?
No. Medicare pays it through the CLFS, with one national amount across states and localities and no office-versus-facility adjustment.
What should the documentation identify?
It should identify the antibody analysis as directed at Coxiella burnetii.
Is this a general fever test?
No. It represents antibody analysis directed at the specific bacterium associated with Q fever.
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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