CPT code 84300: Urine sodium, urine specimen2026 Medicare lab fee · Clinical Laboratory Fee Schedule
This laboratory assay measures sodium in urine and is used to evaluate renal sodium handling, fluid balance, and electrolyte disorders.
Medicare pays $5.06 for 84300 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
$5.06
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 84300 covers
The assay measures sodium in a urine specimen. Clinicians use the result when evaluating fluid and electrolyte disorders, including hyponatremia, and when assessing kidney handling of sodium in settings such as acute kidney injury. Nephrologists, hospitalists, and other clinicians may order it as part of an evaluation that also includes serum electrolytes, urine creatinine, or urine osmolality. The laboratory reports the urine sodium result for the specimen tested.
Report 84300 for the urine sodium assay, not for sodium measured in serum or sweat. The urine specimen distinguishes this assay from those tests. Medicare pays this test under the CLFS at one national amount per code, without locality or office-versus-facility adjustment; the 2026 national amount is $5.06, unchanged since 2020. The test is paid only from 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 84300
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 84300. 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 84300 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84300 on the lab fee schedule since 2020
84300 · CLFS 2026 Q4 (current)
$5.06
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.
84300 compared with similar tests
- 84295Sodium testSerum, plasma, or whole blood$4.81
- 84295 reports sodium measured in serum, plasma, or whole blood; 84300 reports sodium measured in urine.
- 84302Sweat sodiumQuantitative sweat measurement$4.86
- 84302 measures sodium in sweat, whereas 84300 measures sodium in urine.
- 83935Urine osmolalityUrine specimen$6.82
- 83935 measures urine osmolality, a measure of urine concentration; 84300 measures sodium in urine.
84300 billing questions
How does this differ from a serum sodium test?
84300 measures sodium in urine. Sodium measured in serum, plasma, or whole blood is reported with 84295.
Is this the correct code for sweat sodium?
No. Use 84302 for sodium measured in sweat; 84300 is for urine.
Is urine sodium commonly ordered with other tests?
It may be ordered with serum sodium, urine osmolality, or urine creatinine when evaluating fluid balance, electrolyte disorders, or kidney function.
Can urine sodium and urine osmolality be reported together?
Yes. They are distinct tests that may be ordered together when evaluating fluid balance or kidney handling of sodium.
How does Medicare pay for 84300?
Medicare pays it under the CLFS at one national amount per code, with no geographic or office-versus-facility adjustment.
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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