CPT code 84442 describes a laboratory assay performed by a lab analyst to measure thyroxine binding globulin (TBG) concentration in patient serum; this is a clinical chemistry test used in the evaluation of thyroid hormone binding and is typically performed as a pathology/laboratory service in a clinical laboratory or hospital laboratory setting.

For related coverage guidance, see recent payer policy updates: Salivary Hormone Testing, Parathyroid Hormone, Phosphorus, Calcium, and Magnesium Testing, Bone Turnover Markers Testing.