CPT code 0459U designates a Proprietary Laboratory Analyses (PLA) assay for the Elecsys® Total Tau CSF (tTau) and β–Amyloid (1–42) CSF II (Abeta 42) Ratio from Roche Diagnostics. The test uses cerebrospinal fluid and an electrochemiluminescent immunoassay (ECLIA) to produce a tTau/Abeta42 ratio that can inform evaluation of patients with cognitive impairment. As a PLA code, 0459U applies to a single manufacturer-specific test and carries implications for coding specificity, billing clarity, and payer coverage determinations nationally.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise national overview of clinical context, common sites of service, and the coding scope for this manufacturer‑specific CSF biomarker assay. The publication outlines payer relevance and typical contractual considerations for PLA codes, summarizes expected use cases in cognitive impairment assessment, and highlights where Data not available in the input limits further detail. This brief provides clinicians, laboratory directors, and billing professionals with the essential facts about CPT code 0459U, its clinical purpose, and the national payer landscape to inform administrative and clinical workflows.