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    v1.0.28
    OpenPayerBilling CodesHematology and Coagulation ProceduresCPT cpt-85810-serum-viscosity-test-laboratory
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    CPT 85810: Serum Viscosity Test

    CPT code 85810 describes a laboratory procedure in which a medical laboratory analyst measures the viscosity of patient serum to evaluate blood protein concentration and flow properties; the service is a clinical pathology laboratory test typically performed in a hospital or independent clinical laboratory setting using standard viscometry techniques for diagnostic and monitoring purposes.

    For related coverage guidance, see recent payer policy updates: Epithelial Cell Cytology in Breast Cancer Risk Assessment, Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only), Antibody-Drug Conjugates.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult inpatient or outpatient undergoing laboratory evaluation for suspected hyperproteinemia, paraproteinemia, severe dehydration, or conditions affecting serum rheology (for example, monoclonal gammopathy, multiple myeloma, Waldenström macroglobulinemia, or severe hyperviscosity syndromes). A 62-year-old male presents with progressive visual disturbance, headache, and epistaxis. Basic metabolic panel and complete blood count are obtained; serum protein electrophoresis suggests a monoclonal spike. The clinician orders a serum viscosity measurement to quantify whole serum viscosity to guide urgent therapeutic decisions (plasmapheresis vs medical management).

    Workflow: Blood is drawn into appropriate tubes, labeled, and transported to the clinical laboratory. The lab analyst performs 85810 (serum viscosity test) using viscometry, documents results in the laboratory information system, and communicates critical high values to the ordering clinician. Results are used alongside electrophoresis, immunofixation, and complete blood counts to determine diagnosis and therapeutic urgency. Typical site of service is the hospital clinical laboratory or independent diagnostic laboratory; specimen collection occurs in inpatient wards, emergency department, or ambulatory phlebotomy sites.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    84165Serum protein electrophoresis; quantitativeOften performed alongside 85810 to characterize paraproteins contributing to increased serum viscosity.
    86330Immunoglobulin quantitation; IgGUsed to quantify immunoglobulin fractions that may explain elevated viscosity.
    86331Immunoglobulin quantitation; IgAComplements IgG testing when evaluating monoclonal or polyclonal gammopathies.
    86332Immunoglobulin quantitation; IgMParticularly relevant when Waldenström macroglobulinemia or high IgM causes hyperviscosity.
    36514Therapeutic apheresis; plasma exchange (single volume)Performed after diagnosis of clinically significant hyperviscosity to remove pathogenic proteins; may follow elevated 85810 results.

    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…
    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…
    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…

    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…
    2085R0205XRadiological Physics PhysicianA radiological physicist deals with the diagnostic and therapeutic applications of roentgen rays, gamma rays from sealed sources, ultrasonic radiation…
    261QX0203XRadiation Oncology Clinic/CenterAmbulatory Health Care Facilities · Clinic/Center
    363LP0200XPediatric Nurse PractitionerPhysician Assistants & Advanced Practice Nursing Providers · Nurse Practitioner
    3245S0500XChildren's Substance Abuse Rehabilitation FacilityA facility or distinct part of a facility that provides a 24 hr therapeutically planned living and rehabilitative intervention environment for the tre…
    261QD0000XDental Clinic/CenterAmbulatory Health Care Facilities · Clinic/Center

    Related ICD-10-CM Codes

    26 rows

    ICD-10-CM CodeDescription
    B18.2Chronic viral hepatitis C
    B19.9Unspecified viral hepatitis without hepatic coma
    C83.30Diffuse large B-cell lymphoma, unspecified site
    C92.00Acute myeloblastic leukemia, not having achieved remission
    D47.1Chronic myeloproliferative disease
    D50.9Iron deficiency anemia, unspecified
    D66Hereditary factor VIII deficiency
    D68.9Coagulation defect, unspecified
    E10.65Type 1 diabetes mellitus with hyperglycemia
    E11.65Type 2 diabetes mellitus with hyperglycemia

    Showing 1–10 of 26

    Related Payer Policy Updates

    Specialty: Hematology/Oncology1 / 3

    4 rows

    PolicyPayerEffective Date
    Epithelial Cell Cytology in Breast Cancer Risk AssessmentOscar Health2026-10-01
    Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only)UnitedHealthcare2026-08-01
    Antibody-Drug ConjugatesPremera Bluecross2026-08-01
    Umbilical Cord Blood Harvesting and Storage for Future Use (for Indiana Only)UnitedHealthcare2026-08-01

    Related Codes

    CPT-85002-BLEEDING-TIME-TEST-LABORATORY

    CPT 85002: Bleeding Time Test, Technical Component

    CPT-85004-AUTOMATED-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

    CPT 85004: Automated White Blood Cell Differential

    CPT-85007-MANUAL-DIFFERENTIAL-WHITE-BLOOD-CELL-COUNT

    CPT 85007: Manual Differential White Blood Cell Count

    CPT-85008-BLOOD-SMEAR-MORPHOLOGIC-REVIEW-NO-DIFFERENTIAL

    CPT 85008: Microscopic Blood Smear Examination, No Differential

    CPT-85009-MANUAL-WBC-COUNT-BUFFY-COAT

    CPT 85009: Manual White Blood Cell Count Using Buffy Coat

    CPT-85013-MICROHEMATOCRIT-TEST-LABORATORY-DIAGNOSTIC

    CPT 85013: Microhematocrit Test by Tube Centrifugation

    CPT-85014-HEMATOCRIT-VOLUME-PERCENT-RED-BLOOD-CELLS

    CPT 85014: Hematocrit (Volume Percent of Red Blood Cells)

    CPT-85018-HEMOGLOBIN-ASSAY-WHOLE-BLOOD

    CPT 85018: Hemoglobin Measurement in Whole Blood

    CPT-85025-COMPLETE-BLOOD-COUNT-CBC

    CPT 85025: Complete Blood Count (CBC)

    CPT-85027-COMPLETE-BLOOD-COUNT-HGB-HCT

    CPT 85027: Complete Blood Count with Hemoglobin and Hematocrit

    Showing 1–10 of 99

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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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