Loading...

    Explore
    • Policy Monitoring
    • Live Policy Feed
    • Billing Codes
    • NPI Medicare & Medicaid
    • Healthcare Providers
    • Health Insurance Payers
    • States
    • Service Lines
    • Taxonomy Codes
    Lookup tools
    • Billing Code Lookup
    • CPT Modifier Lookup
    • Provider Taxonomy Code Lookup
    • Healthcare Provider & Facility Lookup
    • Health Insurance Payer Lookup
    • Payer Contact Directory

    Policy & Benchmark Tools

    • Prior Authorization Lookup
    • Coverage Criteria Lookup
    • Timely Filing Lookup
    • Billing Code Reimbursement Rates
    • Payer Comparison Dashboard
    • Facility Comparison Dashboard
    • All tools

    Company

    • About OpenPayer
    • Data Sources
    • Trek Health
    OpenPayerby Trek Health
    LinkedInYouTube

    © 2026 Trek Health. All rights reserved.

    OpenPayer is built and maintained by Trek Health.

    v1.0.28
    OpenPayerBilling CodesChemistry ProceduresCPT cpt-84681-c-peptide-laboratory-assay
    Ask Trek AI about this page

    CPT 84681: C‑peptide Quantitative Test, Serum or Plasma

    CPT code 84681 describes a laboratory quantitative C‑peptide test that measures C‑peptide (a byproduct of endogenous insulin production) in serum or plasma; the service is a clinical laboratory diagnostic assay performed by a lab analyst or technologist and is typically rendered in a clinical laboratory or hospital laboratory setting for evaluation of beta‑cell function and insulin secretion.

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

    Customize your policy alerts

    Sign up for cpt 84681 policy alerts

    Get alerted when payer policies referencing 84681 are released or updated.

    Monitor payer policy activity

    Receive email alerts as soon as relevant payer policies are published or updated.

    Table of contents

    Progress1 / 6

    Explore openpayer tools

    • Billing CodesCPT, HCPCS, DRG & more
    • Reimbursement RatesCommercial vs. Medicare rate reports
    • ProvidersHospitals & facilities
    • PayersPlans & market footprint
    • Taxonomy CodesNUCC specialty codes
    • ModifiersCPT modifiers & usage
    • Prior AuthorizationPA policies by payer & drug
    • Timely FilingFiling deadlines by payer
    • Coverage CriteriaMedical necessity by payer
    • Payer ContactsClaims, PA & appeals contacts
    View all tools

    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult with suspected endogenous insulin dysregulation who presents to an outpatient endocrinology clinic for evaluation of hypoglycemia or poor glycemic control. The clinician orders a C‑peptide blood test to distinguish between endogenous insulin production and exogenous insulin administration. The workflow: the clinician documents the indication (for example, recurrent unexplained hypoglycemia or assessment of endogenous insulin in type 1 versus type 2 diabetes), places a lab order for C‑peptide (technical component billed with 84681), the patient has a peripheral venous blood draw in the clinic or outpatient laboratory, the specimen is sent to the clinical laboratory, a laboratory technologist performs the analytic assay and reports a numeric result with reference range, and the ordering clinician reviews the result and documents interpretation and plan in the medical record. Typical sites of service include outpatient hospital laboratories, independent clinical laboratories, and hospital ambulatory clinic phlebotomy units. Typical clinical modifiers that may apply include those reflecting professional/technical components, emergency department origin, or specimen handling nuances, as well as standard billing modifiers for multiple or staged procedures.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    36415Collection of venous blood by venipunctureSpecimen collection required prior to performing 84681; commonly billed by outpatient clinics or phlebotomy services.
    80053Comprehensive metabolic panelOften ordered alongside C‑peptide to assess glucose, renal and hepatic function that affect interpretation.
    83036Hemoglobin; glycated (A1C)Concurrent test for chronic glycemic control when evaluating diabetes phenotype with C‑peptide.
    82947Glucose; quantitative, blood glucose levelSame‑visit point measurement of glucose to correlate with C‑peptide level for hypoglycemia assessment.
    88305Surgical pathology, gross and microscopic examinationIncluded as a related laboratory procedural code in workflows where tissue pathology and metabolic testing are both performed (contextual ancillary service).

    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…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    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…
    77Modifier 77 indicates that a previously performed procedure or service was legitimately repeated by a different physician or other qualified health care professional. The AMA’s CPT definition…- Use modifier 77 when a basic procedure or service already performed is repeated by a different physician or other qualified health care professional (for example, a second provider independently…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207RC0000XCardiovascular Disease PhysicianAn internist who specializes in diseases of the heart and blood vessels and manages complex cardiac conditions such as heart attacks and life-threaten…
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    207K00000XAllergy & Immunology PhysicianAn allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
    207RI0200XInfectious Disease PhysicianAn internist who deals with infectious diseases of all types and in all organ systems. Conditions requiring selective use of antibiotics call for this…
    207RH0000XHematology (Internal Medicine) PhysicianAn internist with additional training who specializes in diseases of the blood, spleen and lymph. This specialist treats conditions such as anemia, cl…
    2865X1600XOperational (Transportable) Military General Acute Care HospitalA Department of Defense (DoD) health care organization furnishing inpatient care 24 hours per day in "non-fixed" or deployed facilities. Entity is not…
    207ND0101XMOHS-Micrographic Surgery PhysicianThe highly-trained surgeons that perform Mohs Micrographic Surgery are specialists both in dermatology and pathology. With their extensive knowledge o…
    1835G0000XDeactivated - Pharmacist

    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

    • More pages

    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.
    Published by

    Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

    Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.