Used primarily in the synthesis of thyroid hormones, particularly in the production of thyroxine (T4) and reverse T3. It serves as an intermediate in pharmaceutical processes for developing hormone replacement therapies and diagnostic agents related to thyroid function. Its structure closely resembles endogenous iodothyronines, making it valuable in research settings for studying thyroid receptor binding and metabolism. Also utilized in immunoassay development and as a reference standard in analytical chemistry for detecting thyroid-related compounds.