Summary & Overview
CPT 84480: Total T3 Blood Test
CPT code 84480 represents a laboratory test that measures total triiodothyronine (total T3) in patient blood. Total T3 is a key thyroid hormone assay used in diagnosing and monitoring thyroid disorders. Nationally, this test is widely performed across outpatient and inpatient laboratory settings and has implications for endocrine care pathways, medication management, and diagnostic workflows.
Key payers addressed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of billing and clinical context, common modifiers associated with laboratory services, and typical sites of service. The publication summarizes how 84480 is reported in claims, expected clinical indications for ordering total T3, and where this test fits within thyroid function panels. It also highlights benchmarking and policy-relevant considerations such as payer coverage variability, coding accuracy, and the role of lab validation in reimbursement.
The report is intended for health plan analysts, revenue cycle professionals, laboratory managers, and clinicians seeking a clear, national-level briefing on CPT code 84480, its clinical purpose, and billing context. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 84480 describes a laboratory assay in which a lab analyst measures total triiodothyronine (total T3) concentration in a patient blood specimen. The service type is clinical laboratory testing for endocrine function, specifically thyroid hormone measurement. The typical site of service is a clinical laboratory or hospital laboratory performing blood-based diagnostic testing.
Clinical & Coding Specifications
Clinical Context
A 46-year-old outpatient presents to a primary care clinic with persistent fatigue, weight changes, palpitations, and heat intolerance. The clinician orders thyroid function testing including total triiodothyronine to evaluate for hyperthyroidism or thyrotoxicosis. A phlebotomist draws a serum sample during the clinic visit; the specimen is transported to the hospital laboratory. The laboratory analyst performs the 84480 assay to measure total T3 concentration using an immunoassay platform, documents results in the laboratory information system, and releases values to the ordering clinician. Results are reviewed in follow-up to correlate with TSH and free T4 for diagnosis and management.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | When billing only the physician interpretation or professional portion of the lab service, if applicable |
TC | Technical component | When billing only the laboratory's technical component (equipment, reagents, technician time) |