Summary & Overview
HCPCS A9529: Iodine I-131 Sodium Iodide Solution, Diagnostic
HCPCS Level II code A9529 denotes iodine I-131 sodium iodide solution billed per millicurie for diagnostic nuclear medicine procedures, commonly used in thyroid uptake studies and diagnostic imaging. This radiopharmaceutical code matters nationally because it standardizes reporting and reimbursement for a critical diagnostic agent that supports thyroid disease evaluation, cancer staging, and treatment planning. Consistent coding facilitates hospital and clinic billing, quality measurement, and supplier reimbursement across payers.
Key payers covered include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise review of clinical context, typical sites of service, common modifiers applicable to radiopharmaceuticals, and practical benchmarking information where available. The publication outlines how A9529 is applied in diagnostic workflows, implications for claims processing, and common billing considerations for facilities that administer I-131 diagnostic doses.
The piece provides national-level benchmarks and payer policy summaries when available, a clinical synopsis of when diagnostic I-131 is used, and guidance on documentation elements typically associated with billing for radiopharmaceutical diagnostic services. Data not available in the input are noted where applicable.
Billing Code Overview
HCPCS Level II code A9529 represents iodine I-131 sodium iodide solution, diagnostic, per millicurie. This code describes the radiopharmaceutical preparation used for diagnostic nuclear medicine procedures that require measurement or imaging of thyroid function or iodine uptake.
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Service type: Diagnostic radiopharmaceutical administration for nuclear medicine imaging and uptake studies
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Typical site of service: Hospital outpatient imaging centers, nuclear medicine departments, and specialized diagnostic clinics
Clinical & Coding Specifications
Clinical Context
A typical patient is an adult referred to a nuclear medicine clinic for diagnostic thyroid imaging or thyroid uptake measurement. The patient presents with symptoms such as unexplained weight changes, palpable thyroid enlargement, neck discomfort, or abnormal thyroid function tests (elevated or suppressed TSH, abnormal free T4). The ordering clinician (endocrinologist, primary care physician, or otolaryngologist) requests administration of A9529 (Iodine I-131 sodium iodide solution, diagnostic, per millicurie) to perform a radioactive iodine uptake (RAIU) study or to obtain diagnostic images to evaluate thyroid nodules, diffuse goiter, or thyrotoxicosis.
In the clinical workflow, the patient receives pre-procedure counseling regarding radiation safety and potential medication restrictions (e.g., stopping thyroid hormone or iodine-containing medications as appropriate). The nuclear medicine technologist administers a measured diagnostic dose of I-131 per the ordered activity (recorded in millicuries) and documents lot number and activity. Blood or urine tests are not routinely required for the diagnostic dose, but a baseline TSH and free T4 are often available. Imaging is typically performed at set intervals after administration (for example at 4 and 24 hours) using a gamma camera, or uptake is measured with a probe. The interpreting nuclear medicine physician or radiologist documents uptake percentages, interprets focal versus diffuse activity, and provides a report to the referring provider for management decisions (medical therapy, radioactive ablation planning, or surgery). Typical site of service is an outpatient nuclear medicine department, ambulatory imaging center, or hospital radiology/nuclear medicine unit.
Coding Specifications
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