Summary & Overview
CPT 84479: Thyroid Hormone Uptake and Binding Ratio Test
CPT code 84479 represents a laboratory assay measuring thyroid hormone uptake or the thyroid hormone binding ratio, used to evaluate thyroid function and protein-binding dynamics. These assays play a role in diagnostic evaluation of thyroid disorders and can influence subsequent clinical testing or management decisions. Nationally, laboratory codes like 84479 are important for accurate claim submission, clinical interpretation, and tracking utilization of endocrine diagnostic services.
Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of clinical context for the test, typical sites of service, and common payer coverage considerations. The publication summarizes available benchmarks, billing and documentation considerations, and any notable policy updates or coding guidance relevant to processing claims for this laboratory service. It also outlines where to locate authoritative coding references and payer policy language. Data not available in the input is noted where applicable.
Billing Code Overview
CPT code 84479 describes a laboratory procedure in which a lab analyst measures thyroid hormone uptake in patient blood or determines the thyroid hormone binding ratio. The test assesses how thyroid hormones bind to carrier proteins and can aid in evaluating thyroid function.
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Service type: Laboratory diagnostic test, endocrine function assay
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Typical site of service: Clinical laboratory or hospital laboratory setting
Clinical & Coding Specifications
Clinical Context
A 48-year-old female presents to her primary care clinic with fatigue, weight gain, and cold intolerance. The clinician orders thyroid function testing, including a thyroid hormone uptake/binding ratio to help evaluate thyroid status and assess the availability of thyroid hormone binding sites on serum proteins. A phlebotomy technician collects a venous blood specimen; the specimen is routed to the clinical laboratory. A laboratory analyst performs the test to measure thyroid hormone uptake or to calculate the thyroid hormone binding ratio, reported as a numeric result used by the ordering clinician alongside free T4, total T4, total T3, and TSH. Typical workflow steps: order entry by clinician, specimen collection in outpatient or ambulatory laboratory, specimen processing and analysis by clinical laboratory staff, result verification by a laboratory technologist, and electronic reporting to the ordering provider. Typical sites of service include outpatient ambulatory clinics, hospital laboratories, and independent clinical reference laboratories.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when billing only the professional interpretation component separate from the technical laboratory component when payer allows. |
TC |