CPT code 83735: Magnesium2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures magnesium concentration, commonly in blood, to evaluate or monitor magnesium imbalance and conditions or treatments that can affect magnesium levels.
Medicare pays $6.70 for 83735 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
$6.70
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 83735 covers
83735 is a laboratory assay that measures magnesium concentration. Serum or plasma is commonly tested; urine magnesium may be measured when clinicians assess renal magnesium handling or losses. Clinicians order the test when magnesium imbalance is suspected or when monitoring a condition or treatment that can affect magnesium. Clinical laboratories perform the assay for inpatient and outpatient care and report the result for the specimen tested.
Report 83735 for the magnesium assay, not for a specific result or interpretation. It is commonly ordered with chemistry testing such as a basic or comprehensive metabolic panel; neither panel includes magnesium. Report the panel and magnesium assay when both are performed. Medicare pays 83735 through the CLFS at one national amount per code. The 2026 amount is $6.70, unchanged since 2020, and applies across localities without geographic or office-versus-facility adjustment. The test is paid through the CLFS, not 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 83735
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 83735. 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 83735 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83735 on the lab fee schedule since 2020
83735 · CLFS 2026 Q4 (current)
$6.70
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.
83735 compared with similar tests
- 80048Basic metabolic panelTotal calcium$8.46
- Use 80048 for the basic metabolic panel. Report 83735 separately when a magnesium assay is performed, because the panel does not include magnesium.
- 80053Metabolic panelFourteen blood chemistry tests$10.56
- Use 80053 for the comprehensive metabolic panel. Report 83735 separately when a magnesium assay is performed, because the panel does not include magnesium.
- 83785ManganeseHeavy metal level$26.65
- 83785 measures manganese, a different element. Use 83735 for magnesium testing.
83735 billing questions
Does a basic metabolic panel include magnesium?
No. Report 83735 when a magnesium assay is performed; a basic metabolic panel does not include it.
Which specimen is used for 83735?
Serum or plasma is commonly tested. Urine magnesium may also be measured to assess magnesium handling or losses.
Can 83735 be reported with a comprehensive metabolic panel?
Yes, when a separate magnesium assay is performed. A comprehensive metabolic panel does not include magnesium.
How does Medicare pay for 83735?
Medicare pays the test through the CLFS at one national amount per code, with no locality or office-versus-facility adjustment.
How does 83735 differ from 83785?
83735 measures magnesium; 83785 measures manganese.
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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