CPT code 83605: Lactate test, lactic acid, not LDH2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures blood lactate to support evaluation of suspected lactic acidosis, impaired tissue perfusion, shock, or acute metabolic illness.
Medicare pays $11.57 for 83605 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
$11.57
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
- QW · CLIA-waived test
- $11.57
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 83605 covers
Code 83605 reports a laboratory assay that measures lactate, also called lactic acid, in blood. Clinicians commonly order it when evaluating suspected lactic acidosis, impaired tissue perfusion, shock, or acute illness in which lactate elevation may be relevant. Hospital, emergency department, and outpatient laboratories perform the assay; treating clinicians interpret the result with the patient’s clinical findings and other test results.
Medicare pays 83605 through the CLFS, with one national amount across states and localities and no office-versus-facility payment difference. The 2026 national CLFS amount is $11.57, unchanged from 2020 through 2026. CMS lists a QW version for performance by a site holding a CLIA certificate of waiver. The test is paid only under the CLFS and 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 83605
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 83605. 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 83605 with status X (excluded by statute), so the test itself is paid only from the CLFS.
CLIA-waived version (QW)
CMS also lists 83605 with modifier QW, the version labs holding a CLIA certificate of waiver bill. It pays $11.57.
83605 on the lab fee schedule since 2020
83605 · CLFS 2026 Q4 (current)
$11.57
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.
83605 compared with similar tests
83605 billing questions
Does 83605 measure lactate or lactate dehydrogenase?
It measures lactate, also called lactic acid. Lactate dehydrogenase (LDH) is a different enzyme test, reported with codes such as 83615 or 83625.
When may modifier QW be used?
CMS lists a QW version for performance by a site holding a CLIA certificate of waiver. QW identifies the waived-test version.
How does Medicare pay for 83605?
Medicare pays it under the CLFS at one national amount, with no locality or office-versus-facility payment adjustment. The test is paid only under the CLFS.
Is 83605 interchangeable with an LDH assay?
No. Code 83605 measures lactate, while 83615 and 83625 describe LDH enzyme testing.
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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