CPT code 84105: Urine phosphorus, urine specimen2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures phosphate in urine to assess renal phosphate excretion in patients being evaluated for disorders of phosphate balance or kidney stone risk.
Medicare pays $5.78 for 84105 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
$5.78
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 84105 covers
This assay measures phosphate in a urine specimen. It is used in evaluating renal handling of phosphate, including suspected phosphate wasting and other disorders of phosphate balance. Nephrologists, endocrinologists, and other clinicians may order it as part of a renal or metabolic evaluation. The specimen may be a spot or timed collection, according to the clinical order; report the urine assay rather than a serum phosphorus test when the measured material is urine.
Report 84105 for the urine phosphate assay. It may be ordered alongside serum phosphorus or other urine studies when the clinician is assessing renal handling of minerals. Medicare pays the test through the CLFS, not the physician fee schedule. The 2026 national CLFS amount is $5.78 and has remained unchanged since 2020. The same amount applies across states and localities, with no office or facility payment difference.
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 84105
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 84105. 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 84105 with status X (excluded by statute), so the test itself is paid only from the CLFS.
84105 on the lab fee schedule since 2020
84105 · CLFS 2026 Q4 (current)
$5.78
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.
84105 compared with similar tests
- 84100Phosphorus testBlood phosphate level$4.74
- 84100 measures phosphorus in blood; 84105 measures phosphorus in urine. Select according to the specimen tested.
- 84133Urine potassiumUrine specimen$4.73
- 84133 measures urine potassium, a different analyte. Use 84105 for urine phosphate.
- 84156Urine proteinTotal protein$3.67
- 84156 measures urine protein, not phosphate. The specimen type is similar, but the analyte determines the code.
84105 billing questions
When should 84105 be reported instead of 84100?
Use 84105 when the assay measures phosphorus in urine. Use 84100 when the measured specimen is blood.
Does 84105 identify a spot or timed urine collection?
The code identifies the urine phosphorus assay, not a collection duration. The collection type follows the clinician’s order.
Can urine phosphorus be reported with serum phosphorus?
Yes, the tests measure phosphorus in different specimens and may be ordered together to assess renal phosphate handling. Report each test that was performed.
How does Medicare pay for 84105?
Medicare pays it under the CLFS at one national amount per code. Payment is the same across localities and in office and facility settings.
Is a separate physician interpretation included in 84105?
84105 reports the urine phosphorus assay and is paid through the CLFS. It does not identify a separate physician interpretation service.
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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