CPT code 83540: Iron assay, serum iron concentration2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures circulating iron in a patient specimen, commonly ordered during evaluation of anemia, suspected iron deficiency, or possible iron overload.
Medicare pays $6.47 for 83540 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
$6.47
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 83540 covers
The serum iron assay quantifies iron circulating in the blood, principally iron carried by transferrin. Clinicians order it during evaluation of anemia or suspected iron deficiency or iron overload, and to assess iron status alongside other iron-study results. Clinical laboratories perform the measurement on a patient specimen; it is commonly part of an outpatient or hospital laboratory workup.
Report 83540 for the measured iron result; a separately performed iron-binding-capacity test or ferritin test is coded separately. Medicare pays this service only under the CLFS, at one national rate across localities and settings, with no geographic or office/facility adjustment. The 2026 national CLFS amount is $6.47, unchanged since 2020. The test is paid only through the CLFS, rather than 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 83540
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 83540. 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 83540 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83540 on the lab fee schedule since 2020
83540 · CLFS 2026 Q4 (current)
$6.47
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.
83540 compared with similar tests
- 83550Iron bindingBinding capacity$8.74
- 83540 reports circulating iron; 83550 reports iron-binding capacity. Report both when both tests are performed.
- 82728FerritinBlood ferritin level$13.63
- 82728 reports ferritin, a separate measure of stored iron. It does not replace the circulating iron result reported by 83540.
- 84466TransferrinIron-binding protein level$12.76
- 84466 reports a transferrin measurement. Choose it when transferrin is measured rather than the circulating iron measured by 83540.
83540 billing questions
When should 83540 be reported instead of 83550?
Report 83540 for the circulating iron measurement. Report 83550 when iron-binding capacity is measured; both may be reported when both tests are performed.
Is ferritin included in 83540?
No. Ferritin is a separate laboratory measurement and is reported with its own code when performed.
How many units are reported?
Report one unit for each iron assay performed. Do not use this code to represent a separate iron-binding-capacity or ferritin result.
How does Medicare pay for 83540?
Medicare pays the test through the CLFS at a single national rate that applies across localities and settings.
Can a transferrin test be used instead?
Use the code for the test actually performed: 83540 measures circulating iron, while 84466 reports a transferrin measurement.
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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