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    v1.0.28
    OpenPayerBilling CodesChemistry ProceduresCPT cpt-84166-protein-fraction-electrophoresis-nonserum
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    CPT 84166: Protein Fractionation by Electrophoresis, Non-Serum

    Medicare pays $18 on average nationally for this procedure.

    CPT code 84166 describes a laboratory service in which a lab analyst performs electrophoresis to separate and evaluate levels of protein fractions in a non‑serum specimen; this clinical laboratory test (protein fractionation by electrophoresis) is a diagnostic pathology service typically performed in a clinical laboratory or hospital laboratory setting and used to characterize abnormal protein distributions for diagnostic and monitoring purposes.

    For related coverage guidance, see recent payer policy updates: Salivary Hormone Testing, Parathyroid Hormone, Phosphorus, Calcium, and Magnesium Testing, Bone Turnover Markers Testing.

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    Clinical & Coding Specifications

    Clinical Context

    A 62-year-old patient with a history of chronic kidney disease and unexplained proteinuria is referred to the clinical laboratory for protein fractionation by electrophoresis on urine. The clinician orders 84166 to separate and quantify protein fractions in a non-serum specimen to evaluate for monoclonal gammopathy, tubular protein loss patterns, or other dysproteinemias. Specimen collection is performed in the outpatient phlebotomy/collection area or clinic restroom (for urine); the sample is labeled and transported to the clinical laboratory. A medical laboratory scientist performs electrophoresis, documents fractionation patterns, and generates a report including qualitative and quantitative interpretation for the ordering provider. Results are reviewed by the laboratory director when required and transmitted to the provider; the provider integrates findings with serum studies (if available), immunofixation, and clinical data to guide further testing or referral to hematology or nephrology.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    84166Electrophoresis; performed on specimen other than serum, separation and evaluation of protein fractionsThe primary test for protein fractionation in non-serum specimens (urine, CSF, other body fluids).
    83036Protein; total, urine (e.g., 24-hour)Often performed alongside 84166 to quantify total protein excretion prior to fractionation.
    82728Protein, electrophoresis, serum (e.g., SPEP)Serum protein electrophoresis is commonly ordered in parallel to compare serum and non-serum profiles.
    83970Immunoglobulin, quantitative (IgG, IgA, IgM)Performed when electrophoresis suggests monoclonal gammopathy to quantify immunoglobulin levels.
    86336Immunofixation; serum/urine, protein electrophoresis with immunofixation, any methodUsed to identify specific monoclonal proteins following abnormal electrophoresis patterns.

    Related Modifiers

    8 rows

    ModifierDescriptionWhen to Use
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…
    91Modifier 91 — “Repeat Clinical Diagnostic Laboratory Test” — is appended when the exact same CPT laboratory test is performed more than once for the same patient on the same day because serial,…- Use modifier 91 when the exact same CPT laboratory test is performed more than once on the same patient on the same date because serial or repeated testing is medically necessary to monitor…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    76Modifier -76, Repeat Procedure or Service by Same Physician or Other Qualified Health Care Professional, is appended when the same provider performs an identical, medically necessary procedure or…- Use modifier -76 when the same physician or other qualified health care professional performs an identical procedure or service a second (or subsequent) time on the same date of service and the…
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
    95Modifier 95 indicates that a service was provided via synchronous, real‑time audio‑video telehealth rather than in‑person. Per CMS, AAPC and professional associations, append modifier 95 to claim…- Use modifier 95 to indicate a service was furnished via synchronous, real‑time audiovisual telehealth (a live audio‑video conference between patient and provider) rather than in‑person. - Pair…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207Q00000XFamily Medicine PhysicianFamily Medicine is the medical specialty which is concerned with the total health care of the individual and the family. It is the specialty in breadt…
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    208M00000XHospitalist PhysicianHospitalists are physicians whose primary professional focus is the general medical care of hospitalized patients. Their activities include patient ca…
    364SA2200XAdult Health Clinical Nurse SpecialistPhysician Assistants & Advanced Practice Nursing Providers · Clinical Nurse Specialist
    2081P2900XPain Medicine (Physical Medicine & Rehabilitation) PhysicianA physician who provides a high level of care, either as a primary physician or consultant, for patients experiencing problems with acute, chronic or …
    261QA0600XAdult Day Care Clinic/CenterAmbulatory Health Care Facilities · Clinic/Center
    207YP0228XPediatric Otolaryngology PhysicianA pediatric otolaryngologist has special expertise in the management of infants and children with disorders that include congenital and acquired condi…
    237600000XAudiologist-Hearing Aid FitterAn audiologist/hearing aid fitter is the professional who specializes in evaluating and treating people with hearing loss, conducts a wide variety of …

    Related Payer Policy Updates

    Specialty: Endocrinology1 / 3

    10 rows

    PolicyPayerEffective Date
    Salivary Hormone TestingOscar Health2026-10-01
    Parathyroid Hormone, Phosphorus, Calcium, and Magnesium TestingOscar Health2026-10-01
    Bone Turnover Markers TestingOscar Health2026-10-01
    Testosterone — Coverage Criteria for Measurement and MonitoringOscar Health2026-10-01
    Diabetes Mellitus Testing — Coverage CriteriaOscar Health2026-10-01
    Thyroid Disease TestingOscar Health2026-10-01
    Thyroid Disease Testingblue cross blue shield - louisiana2026-09-15
    Thyroid Disease TestingBlue Cross Blue Shield - New Mexico2026-09-04
    Parathyroid Hormone, Phosphorous, Calcium and Magnesium TestingBlue Cross Blue Shield - New Mexico2026-09-04
    Testosterone laboratory testing and managementPremera Bluecross2026-09-04

    Related Codes

    CPT-82009-KETONE-BODIES-QUALITATIVE-TEST

    CPT 82009: Qualitative Ketone Bodies Test

    CPT-82010-QUANTITATIVE-KETONE-BODIES-ASSAY-SERUM-PLASMA

    CPT 82010: Quantitative Ketone Bodies in Serum or Plasma

    CPT-82013-ACETYLCHOLINESTERASE-QUANTITATIVE-ASSAY

    CPT 82013: Quantitative Acetylcholinesterase (Acetylhydrolase) Assay

    CPT-82016-QUALITATIVE-ACYLCARNITINES-METABOLIC-SCREEN

    CPT 82016: Qualitative Acylcarnitines, Plasma/Serum/Urine

    CPT-82017-QUANTITATIVE-ACYLCARNITINE-ANALYSIS

    CPT 82017: Quantitative Acylcarnitine Analysis

    CPT-82024-QUANTITATIVE-CORTICOTROPIN-ACTH-ASSAY

    CPT 82024: Adrenocorticotropic Hormone (ACTH) Quantitative Assay

    CPT-82030-QUANTITATIVE-CAMP-PLASMA-URINE-ASSAY

    CPT 82030: Quantitative cyclic AMP assay on plasma or urine

    CPT-82040-QUANTITATIVE-ALBUMIN-MEASUREMENT

    CPT 82040: Quantitative Albumin Measurement

    CPT-82042-QUANTITATIVE-ALBUMIN-NONBLOOD-FLUID

    CPT 82042: Albumin Quantitation in Non-Blood Body Fluid

    CPT-82043-URINE-ALBUMIN-QUANTITATION-KIDNEY-DISEASE

    CPT 82043: Urine Albumin Quantitative Assay

    Showing 1–10 of 411

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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