CPT code 84591: Vitamin assay, vitamin not otherwise specified2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Reports a laboratory measurement of a vitamin when the assay is not identified by a more specific vitamin code.
Medicare pays $17.06 for 84591 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
$17.06
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 84591 covers
Code 84591 identifies a laboratory assay measuring a vitamin when no more specific vitamin assay code describes the test performed. It distinguishes an unspecified vitamin assay from separately identified assays, including vitamin A (84590) and vitamin K (84597). Laboratories report this code for the vitamin assay performed when a more specific vitamin code does not describe that assay. A vitamin-specific code is used when the assay is identified by that code.
Medicare pays 84591 through the CLFS at one national amount per code in every state and locality, without geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $17.06, unchanged from 2020 through 2026. The test is paid only through the CLFS, with no separate physician fee schedule payment.
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 84591
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 84591. 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 84591 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84591 on the lab fee schedule since 2020
84591 · CLFS 2026 Q4 (current)
$17.06
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.
84591 compared with similar tests
- 84590Vitamin A$11.61
- 84590 identifies a vitamin A assay. Use 84591 when the performed vitamin assay is not otherwise specified.
- 84597Vitamin K assay$13.72
- 84597 identifies a vitamin K assay. Use 84591 for a vitamin assay without a more specific code.
- 82306Vitamin D test25-hydroxy level$29.60
- 82306 is for 25-hydroxy vitamin D testing. It is more specific than 84591 when that assay was performed.
- 82652Vitamin D1,25-dihydroxy form$38.50
- 82652 is for 1,25-dihydroxy vitamin D testing. Choose it instead of 84591 when that specific assay was performed.
84591 billing questions
When should a laboratory report 84591 instead of a specific vitamin code?
Use 84591 when the vitamin assay performed is not identified by a more specific vitamin code. When the assay measures a specifically coded vitamin, report the code for that vitamin instead.
Does 84591 identify which vitamin was measured?
The code represents a vitamin assay without naming a specific vitamin. The laboratory documentation should identify the assay performed.
Should 84591 be used for vitamin D testing?
Use the vitamin D code that matches the assay performed, such as 82306 for 25-hydroxy vitamin D or 82652 for 1,25-dihydroxy vitamin D.
How does Medicare pay for 84591?
Medicare pays the test through the CLFS at one national amount per code, without geographic or office-versus-facility adjustment.
Does 84591 have a separate physician fee schedule payment?
No. The test is paid only from the CLFS.
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
Fee sheets · Coming soon
Put 84591 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Join the waitlist