Summary & Overview
CPT 85810: Serum Viscosity Test, Laboratory Diagnostic
CPT code 85810 represents a laboratory diagnostic assay that measures the viscosity of patient serum. Serum viscosity testing can aid in the evaluation of disorders that alter serum protein composition or concentration, including monoclonal gammopathies and inflammatory states. As a specialized laboratory service, this code is relevant to clinical laboratories, hospital laboratories, and referring clinicians overseeing diagnostic workups. Nationally, accurate coding for 85810 supports appropriate claims adjudication, clinical interpretation, and quality measurement for laboratory diagnostic services. Key payers referenced in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find: benchmarks for service utilization and reimbursement where available; clinical context on when serum viscosity testing is ordered and how it informs diagnosis; and policy considerations affecting laboratory test coverage and billing. Data gaps are noted where input information is not available. The report is written for a national audience and focuses on coding definition, clinical purpose, and payer coverage context for CPT code 85810.
Billing Code Overview
CPT code 85810 describes a laboratory test in which a lab analyst evaluates the viscosity of patient serum. This is a diagnostic laboratory service that measures the resistance of serum to flow, used to assess alterations in blood protein concentrations and plasma rheology.
Service type: Laboratory diagnostic test
Typical site of service: Clinical laboratory or hospital laboratory
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.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component |