How much does Medicare pay for CPT 84166?

Medicare allowed an average of $17.39 per service and paid $16.10 of that, the balance being the patient's coinsurance and deductible (2024 data). Providers submitted an average of $97.31, which is what they billed rather than what they received — Medicare pays its fee schedule regardless of the charge.

What is CPT code 84166?

Protein measurement, body fluid. It was billed 194,516 times to 165,150 Medicare beneficiaries by 902 providers in 2024.

Does 84166 pay differently in an office than a hospital?

Yes. The allowed amount averaged $17.42 in an office setting and $17.34 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 84166 most?

Clinical Laboratory, with 115,474 services from 161 clinicians. Next are Pathology, Internal Medicine, Hematology-Oncology.

CPT 84166

Protein measurement, body fluid

$17.39Medicare-allowed amount per service, averaged across 194,516 services

Providers submitted

$97.31

Asking price, not received

Medicare allowed

$17.39

The fee schedule figure

Medicare paid

$16.10

Balance is patient coinsurance

Providers submitted an average of $97.31 for this code and Medicare allowed $17.39 — 5.6× 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 $16.10 (93%); the rest is the patient’s coinsurance and deductible.

Office pays differently to hospital

Office / non-facility: $17.42
Hospital / facility: $17.34

The office rate is higher because the practice supplies the room, staff and equipment out of that payment. In a hospital the facility bills those separately, so the clinician's share is smaller — the total cost to Medicare is usually higher, not lower. 127,151 services were billed in an office setting and 67,365 in a facility.

Services: 194,516
Beneficiaries: 165,150
Providers billing it: 902
Total allowed: $3,382,633

What Medicare pays for CPT 84166

Across 194,516 services billed by 902 providers to 165,150 beneficiaries, Medicare allowed an average of $17.39 per service. That is 1.2 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 84166

Specialty	Services	Beneficiaries	Avg allowed	Providers
Clinical Laboratory	115,474	97,934	$17.42	161
Pathology	77,011	65,312	$17.35	713
Internal Medicine	1,188	1,151	$17.65	9
Hematology-Oncology	446	401	$17.38	11
Rheumatology	161	154	$18.75	2
Medical Oncology	107	71	$17.69	3
Hematology	94	93	$16.81	1
General Surgery	24	23	$18.79	1
Physician Assistant	11	11	$17.47	1

84166 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
New Jersey	22,174	$17.51	$17.42	38
Texas	20,046	$17.31	$17.23	41
California	19,549	$17.85	$16.09	73
Florida	17,562	$17.38	$16.47	62
North Carolina	13,456	$17.34	$16.77	24
Massachusetts	8,722	$17.99	$14.26	27
Ohio	8,449	$16.98	$14.81	65
New York	7,546	$18.01	$14.54	49
Illinois	7,459	$17.61	$14.09	64
Georgia	6,069	$17.36	$16.46	30
Pennsylvania	6,060	$17.21	$16.77	34
Michigan	5,099	$16.98	$12.95	45
Tennessee	4,678	$16.08	$14.51	18
Arizona	4,552	$17.46	$17.36	8
Alabama	4,551	$17.14	$16.19	19
Minnesota	3,981	$17.33	$16.59	24
Maryland	3,719	$17.56	$16.87	25
Wisconsin	3,342	$16.84	$14.70	22
Kansas	2,824	$17.31	$17.13	6
Washington	2,823	$17.75	$15.71	15
Virginia	2,539	$17.08	$14.44	15
Connecticut	1,814	$17.90	$12.98	15
Colorado	1,581	$17.37	$17.14	7
Oklahoma	1,351	$16.93	$17.16	13
Nevada	1,157	$17.46	$17.38	2
Arkansas	1,155	$16.10	$16.25	4
Indiana	1,102	$16.73	$13.68	14
Nebraska	1,089	$16.93	$15.36	7
Hawaii	1,065	$17.82	$15.38	4
Iowa	1,043	$17.09	$13.76	11
Missouri	977	$16.77	$13.21	25
Utah	966	$16.72	$14.00	8
Maine	786	$17.00	$14.14	7
Rhode Island	609	$17.46	$14.32	7
Oregon	561	$17.47	$16.20	9
New Mexico	519	$17.96	$16.26	2
Delaware	446	$16.88	$16.03	2
North Dakota	434	$16.89	$12.92	5
South Dakota	398	$17.17	$15.59	8
Louisiana	361	$17.13	$17.27	7
Kentucky	339	$17.01	$13.57	9
Idaho	333	$16.48	$12.97	9
South Carolina	307	$16.52	$13.21	4
New Hampshire	267	$16.91	$12.98	4
Puerto Rico	197	$16.99	$17.47	5
District of Columbia	141	$18.03	$16.92	2
ZZ	87	$17.28	$16.96	1
Mississippi	82	$16.55	$17.04	2
Montana	76	$17.06	$13.35	2
West Virginia	37	$16.86	$12.70	1
U.S. Virgin Islands	20	$15.95	$17.47	1
Vermont	16	$16.52	$12.69	1

Related codes

84153Psa (prostate specific antigen) measurement$17.98
84100Phosphate level$4.63
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
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.