CPT code 0358U designates the Lumipulse® G βAmyloid Ratio (1–42/1–40) Test, a proprietary cerebrospinal fluid (CSF) assay by Fujirebio Diagnostics that measures the ratio of β‑Amyloid 1–42 to 1–40 using chemiluminescence enzyme immunoassay. As a PLA code, 0358U is uniquely tied to a single manufacturer’s test and is used for reporting and billing that specific Alzheimer’s disease–related biomarker analysis. Nationally, PLA codes like 0358U matter because they standardize reporting for proprietary assays and influence coverage determinations, laboratory billing practices, and utilization monitoring.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The analysis covers payer coverage patterns, coding guidance, and the clinical context for CSF β‑Amyloid ratio testing in cognitive impairment and Alzheimer’s disease evaluation. Readers will find benchmarks for payer adoption, summaries of policy directions affecting proprietary CSF biomarker tests, and a clinical synopsis of the test’s intended use and typical laboratory setting. Data not available in the input are noted where applicable; the report focuses on clarifying what 0358U represents, its service setting, and how it is positioned within laboratory billing for Alzheimer’s disease diagnostics.