CPT code 83930: Blood osmolality, blood specimen2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures blood osmolality to assess the concentration of dissolved particles, often during evaluation of sodium abnormalities, altered water balance, or a possible osmolar gap.
Medicare pays $6.61 for 83930 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
$6.61
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 83930 covers
This laboratory assay measures the concentration of dissolved particles in a blood specimen. Clinicians may order it when evaluating hyponatremia or hypernatremia, changes in water balance, or a suspected osmolar gap, including in some evaluations for toxic alcohol exposure. Clinical chemistry laboratories typically perform the assay for outpatient or hospital-based care.
Report this code for the blood osmolality measurement; urine osmolality is a separate service. Medicare pays it through the CLFS, with one national amount applying across states and localities and no office-versus-facility payment difference. The 2026 national CLFS amount is $6.61, unchanged since 2020. The test is paid only 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 83930
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 83930. 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 83930 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83930 on the lab fee schedule since 2020
83930 · CLFS 2026 Q4 (current)
$6.61
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.
83930 compared with similar tests
- 83935Urine osmolalityUrine specimen$6.82
- Use 83930 for a blood specimen and 83935 for a urine specimen. The specimen tested distinguishes these related osmolality assays.
- 80048Basic metabolic panelTotal calcium$8.46
- The basic metabolic panel measures a group of chemistry analytes, not blood osmolality. Report 83930 when an osmolality measurement is performed.
- 84295Sodium testSerum, plasma, or whole blood$4.81
- Code 84295 reports a sodium measurement; 83930 reports blood osmolality. These are distinct tests that may both be ordered during an electrolyte evaluation.
83930 billing questions
When should I report blood rather than urine osmolality?
Report this code for the osmolality measurement on a blood specimen. Use 83935 for a urine osmolality measurement.
Is blood osmolality included in a basic metabolic panel?
A basic metabolic panel does not measure osmolality. When both tests are performed and appropriate for the encounter, report each service performed.
Does Medicare pay this test under the physician fee schedule?
No. Medicare pays this test through the CLFS; it is excluded from the physician fee schedule.
Does the CLFS amount vary by location or setting?
No. One national amount applies across states and localities, with no office-versus-facility payment difference.
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 83930 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Join the waitlist