Summary & Overview
CPT 83519: Radioimmunoassay for Unassigned Analyte
CPT code 83519 denotes a laboratory test performed by radioimmunoassay for analytes that lack a more specific billing code. Nationally, this code matters because radioimmunoassay remains a valid methodology for measuring certain hormones, drugs, and biochemical markers when alternative specific codes are not applicable. Use of 83519 affects lab billing workflows, claims adjudication, and reporting when assays are method-based rather than analyte-specific. Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical and billing context for radioimmunoassay procedures, typical sites of service, common modifiers, and which payers are commonly involved in reimbursement and claims processing. The publication also outlines expected benchmarks and policy considerations relevant to labs and billing staff, highlights how 83519 is used when no analyte-specific CPT code exists, and summarizes practical implications for revenue cycle and coding compliance. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 83519 describes a laboratory procedure in which the analyte is measured by radioimmunoassay. This code is used when the procedure uses radioimmunoassay methodology and no more specific analyte-assigned code is available.
Service Type: Laboratory — immunoassay (radioimmunoassay) testing
Typical Site of Service: Clinical laboratory or hospital laboratory
Clinical & Coding Specifications
Clinical Context
A typical patient is a 45-year-old adult referred to a clinical laboratory for measurement of an uncommon peptide or small molecule where the laboratory uses a radioimmunoassay (RIA) methodology and no analyte-specific CPT code exists. The patient presents after a specialty clinic visit (endocrinology, toxicology, or research protocol) with an order for quantitative measurement of an analyte to assist diagnosis or monitoring (for example, an investigational hormone fragment, rare cytokine, or research drug metabolite measured by RIA). A phlebotomy appointment is scheduled in an outpatient laboratory or hospital outpatient draw station. The specimen is collected by venipuncture, labeled, and transported to the clinical or reference laboratory where a medical technologist or laboratory scientist performs radioimmunoassay testing. Results are reported to the ordering clinician, and the professional component (interpretation/sign-out) may be billed separately if applicable. Typical sites of service include hospital outpatient laboratory, independent clinical laboratory, and academic/research laboratory. Common clinical workflows include specimen accessioning, assay calibration and controls, performance of the RIA, quality control verification, result validation by a qualified laboratorian, and transmission of results to the ordering clinician.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation component performed by a qualified laboratorian/physician separate from the technical lab work |