CPT code 83935: Urine osmolality, urine specimen2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures urine concentration to help evaluate the kidneys’ concentrating ability and investigate disorders involving water balance, sodium, or urine output.
Medicare pays $6.82 for 83935 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
$6.82
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 83935 covers
This laboratory assay measures the concentration of a urine specimen. Clinicians use urine osmolality when evaluating water balance and kidney concentrating ability, including patients with abnormal urine output or sodium levels. It can help distinguish among causes of hyponatremia and polyuria, including suspected disorders of water regulation. The test is performed by a clinical laboratory on urine; it may be ordered alongside blood osmolality and electrolyte testing as part of the same evaluation.
Report 83935 for the urine osmolality assay, not for a blood osmolality measurement or a urine dipstick estimate of concentration. Medicare pays it only through the CLFS. The 2026 national CLFS amount is $6.82, unchanged since 2020; the same amount applies across localities, with no office-versus-facility difference. The code is excluded from the physician fee schedule, so payment is through the CLFS rather than a separate physician interpretation component.
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 83935
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 83935. 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 83935 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83935 on the lab fee schedule since 2020
83935 · CLFS 2026 Q4 (current)
$6.82
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.
83935 compared with similar tests
- 83930Blood osmolalityBlood specimen$6.61
- 83930 measures osmolality in blood; 83935 measures it in urine. Select the code according to the specimen tested.
- 81003UrinalysisAutomated, without microscopy$2.25
- A urinalysis without microscopy can include urine specific gravity. It does not represent a urine osmolality assay.
- 84300Urine sodiumUrine specimen$5.06
- 84300 measures urine sodium concentration, not total urine osmolality. The tests answer different questions and may be ordered together.
83935 billing questions
When should 83935 be used instead of 83930?
Use 83935 for an osmolality measurement on urine. Code 83930 is for a blood osmolality measurement.
Is urine osmolality the same as urine specific gravity?
No. Urine osmolality measures the concentration of dissolved particles; specific gravity is a different urine measurement, often included in urinalysis.
Can blood osmolality be reported with urine osmolality?
Yes, when both assays are performed as part of the patient’s evaluation. The blood and urine measurements are reported with their respective codes.
Does Medicare pay 83935 under the physician fee schedule?
No. Medicare pays this test through the CLFS, with one national amount across localities and no office-versus-facility difference.
What specimen supports 83935?
A urine specimen supports this code. A blood specimen belongs to the blood osmolality code, 83930.
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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