CPT 84439: Free Thyroxine (Free T4) Assay, Serum
Commercial payers pay $25 on average nationally for this procedure.
CPT code 84439 reports a laboratory measurement of free thyroxine (free T4) in patient serum; this service is a clinical chemistry lab test typically performed in a hospital or outpatient laboratory setting to evaluate thyroid function and guide diagnosis of thyroid disorders.
For related coverage guidance, see recent payer policy updates: Salivary Hormone Testing, Parathyroid Hormone, Phosphorus, Calcium, and Magnesium Testing, Bone Turnover Markers Testing.
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National Reimbursement Benchmarks
National commercial pricing for CPT 84439 centers around BUCA’s average commercial benchmark of $24.8, with Blue Cross Blue Shield showing the highest dispersion and outliers — BCBS’s 75th–25th interquartile range is $17.4 ($43.0 − $27.6), reflecting substantial upward variability and a long upper tail (max $164.7). Aetna and Cigna show moderate central tendencies but differ in spread: Aetna’s IQR is $6.9 ($12.7 − $6.8), while Cigna’s IQR is $7.9 ($13.0 − $5.1), indicating relatively tighter clustering around their medians compared with BCBS.
UnitedHealth Group displays the tightest interquartile spread at $5.0 ($9.0 − $4.0), suggesting more consistent commercial reimbursement levels near its median of $5.40. Overall, payers vary notably in dispersion: Blue Cross Blue Shield is the widest, UnitedHealth Group the tightest, and BUCA’s mean positions it above several payers’ medians, highlighting a mid-to-upper commercial benchmark for this code.