How much does Medicare pay for CPT 84100?

Medicare allowed an average of $4.63 per service and paid $4.63 of that, the balance being the patient's coinsurance and deductible (2024 data). Providers submitted an average of $26.66, which is what they billed rather than what they received — Medicare pays its fee schedule regardless of the charge.

What is CPT code 84100?

Phosphate level. It was billed 1,763,002 times to 956,744 Medicare beneficiaries by 3,236 providers in 2024.

Does 84100 pay differently in an office than a hospital?

Yes. The allowed amount averaged $4.63 in an office setting and $4.64 in a facility. The office rate is generally higher because the practice supplies the room, staff and equipment out of that single payment; in a hospital those are billed separately by the facility.

Which specialty bills 84100 most?

Clinical Laboratory, with 1,222,383 services from 604 clinicians. Next are Hematology-Oncology, Internal Medicine, Nephrology.

CPT 84100

Phosphate level

$4.63Medicare-allowed amount per service, averaged across 1,763,002 services

Providers submitted

$26.66

Asking price, not received

Medicare allowed

$4.63

The fee schedule figure

Medicare paid

$4.63

Balance is patient coinsurance

Providers submitted an average of $26.66 for this code and Medicare allowed $4.63 — 5.8× less. That gap is normal and means nothing on its own: Medicare pays its fee schedule regardless of what is billed, so the submitted figure describes a hospital chargemaster, not a price anyone paid. Of the allowed amount Medicare paid $4.63 (100%); the rest is the patient’s coinsurance and deductible.

Office pays differently to hospital

Office / non-facility: $4.63
Hospital / facility: $4.64

The facility rate is higher for this code, which is unusual and generally means the service depends on equipment or staffing a hospital carries. 1,762,304 services were billed in an office setting and 698 in a facility.

Services: 1,763,002
Beneficiaries: 956,744
Providers billing it: 3,236
Total allowed: $8,162,699

What Medicare pays for CPT 84100

Across 1,763,002 services billed by 3,236 providers to 956,744 beneficiaries, Medicare allowed an average of $4.63 per service. That is 1.8 services per beneficiary, so this is a code patients typically receive more than once. The allowed amount is the figure that matters: it is what Medicare and the patient together owe, set by the fee schedule and adjusted for local practice costs. What a provider chose to submit has no bearing on it.

Who bills 84100

Specialty	Services	Beneficiaries	Avg allowed	Providers
Clinical Laboratory	1,222,383	703,239	$4.63	604
Hematology-Oncology	131,936	54,208	$4.63	381
Internal Medicine	87,235	44,836	$4.64	548
Nephrology	72,229	31,350	$4.64	283
Nurse Practitioner	56,380	14,225	$4.64	264
Family Practice	40,168	26,672	$4.63	396
Medical Oncology	36,867	13,777	$4.63	87
Pathology	33,834	16,540	$4.63	56
Endocrinology	28,977	19,433	$4.64	234
Rheumatology	19,443	11,351	$4.64	103
Hematology	4,866	2,288	$4.63	11
Physician Assistant	4,696	3,657	$4.63	90
Hospitalist	3,704	2,007	$4.65	8
Cardiology	3,204	2,213	$4.65	11
Gastroenterology	2,241	1,309	$4.57	7

84100 reimbursement by state

Two different numbers. Allowed is what Medicare actually allowed in that state, which includes the local practice-cost adjustment. Standardized strips that geographic adjustment out of the payment, so it is the column to use when comparing states — a difference there reflects how the code was billed, not what it costs to run a practice locally.

State	Services	Allowed	Standardized pmt	Providers
California	247,065	$4.64	$4.65	248
New Jersey	242,749	$4.62	$4.63	93
New York	169,099	$4.64	$4.65	365
Arizona	140,763	$4.62	$4.63	114
Texas	133,537	$4.64	$4.65	203
Florida	127,002	$4.64	$4.65	243
North Carolina	112,167	$4.64	$4.64	133
Ohio	42,835	$4.63	$4.64	70
Alabama	39,915	$4.62	$4.63	75
Illinois	38,354	$4.64	$4.65	125
Massachusetts	38,111	$4.65	$4.65	160
Tennessee	33,158	$4.62	$4.64	191
Arkansas	32,793	$4.62	$4.65	89
Oklahoma	31,566	$4.62	$4.64	37
Michigan	28,486	$4.63	$4.65	91
Georgia	27,575	$4.64	$4.65	86
Pennsylvania	27,151	$4.64	$4.65	49
Maryland	24,257	$4.63	$4.65	39
Kansas	21,654	$4.64	$4.65	31
Virginia	20,712	$4.63	$4.65	76
South Carolina	19,340	$4.63	$4.66	60
Washington	19,148	$4.63	$4.64	34
Wisconsin	18,765	$4.57	$4.65	30
Minnesota	14,359	$4.63	$4.65	64
Louisiana	12,379	$4.62	$4.64	49
Nevada	11,393	$4.64	$4.65	16
Missouri	10,401	$4.64	$4.66	55
Colorado	8,126	$4.63	$4.64	28
Nebraska	7,713	$4.63	$4.64	39
Hawaii	7,644	$4.51	$4.52	4
Iowa	7,008	$4.63	$4.65	48
Oregon	6,476	$4.61	$4.64	29
New Mexico	6,455	$4.62	$4.65	15
Indiana	6,347	$4.63	$4.65	33
Mississippi	5,780	$4.61	$4.65	37
South Dakota	4,180	$4.64	$4.65	15
Kentucky	3,297	$4.61	$4.65	30
Utah	2,846	$4.63	$4.65	17
Connecticut	2,310	$4.50	$4.51	16
Maine	2,057	$4.60	$4.63	17
Rhode Island	1,705	$4.64	$4.65	2
Idaho	1,319	$4.60	$4.65	8
North Dakota	1,013	$4.64	$4.65	11
Puerto Rico	810	$4.63	$4.63	13
Montana	610	$4.65	$4.65	7
U.S. Virgin Islands	588	$4.65	$4.65	3
Wyoming	409	$4.63	$4.65	12
West Virginia	403	$4.63	$4.65	8
District of Columbia	400	$4.63	$4.65	4
Delaware	345	$4.65	$4.65	3
Alaska	192	$4.58	$4.65	7
New Hampshire	135	$4.64	$4.64	2
Guam	100	$4.51	$4.65	2

Related codes

84153Psa (prostate specific antigen) measurement$17.98
84156Total protein level$3.59
84165Protein measurement$13.51
84155Total protein level$3.55
84154Psa (prostate specific antigen) measurement$18.00
84132Blood potassium level$4.63
84166Protein measurement$17.39
84144Progesterone (reproductive hormone) level$20.40
84146Prolactin (milk producing hormone) level$18.95
84134Prealbumin (protein) level$14.28
84133Urine potassium level$4.64
84105Urine phosphate level$5.66

Billing this code is not the same as earning it

An allowed amount is revenue to a practice, not income to a clinician. It funds staff, premises, equipment and supplies before anyone is paid. What clinicians actually earn is published separately by the Department of Labor, and what industry pays them is published separately again by CMS — this site carries both.

What doctors are paid →·Look up a clinician →·All procedure codes →

Where this comes from. CMS Medicare Physician & Other Practitioners, by Provider and Service, 2024. It covers fee-for-service Original Medicare Part B only — not Medicare Advantage, not Medicaid, and not commercial insurance, which typically pays more for the same code.

How it is averaged. CMS publishes one average per provider per code. Every figure here is re-weighted by the number of services, so a clinician who billed the code 4,000 times counts 4,000 times more than one who billed it twice. CMS also suppresses any provider-code pair with fewer than 11 beneficiaries, so low-volume practice is missing from these totals by design.