Summary & Overview
CPT 0445U: Elecsys pTau181/Abeta42 CSF Ratio Assay
CPT code 0445U is a Proprietary Laboratory Analyses (PLA) code for the Elecsys® Phospho–Tau (181P) CSF and β–Amyloid (1–42) CSF II Ratio test from Roche Diagnostics. The assay produces a pTau181/Abeta42 ratio from cerebrospinal fluid using an electrochemiluminescent immunoassay (ECLIA). This biomarker ratio is used in the clinical evaluation of patients with cognitive impairment and may inform diagnostic discussions about Alzheimer disease pathology.
Key national payers examined include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise briefing on the clinical context for CSF biomarker testing, the specific scope and exclusivity implied by the PLA code, and what the code represents for laboratory services and sites of care. The publication summarizes payer coverage considerations, coding and billing practice implications, and the typical service settings where the test is performed. Policy updates and benchmark comparisons relevant to PLA-coded, manufacturer-specific laboratory tests are outlined to help clinical administrators and billing professionals understand how this code fits into broader laboratory and cognitive neurology workflows.
Data not available in the input for associated taxonomies, ICD-10 diagnoses, related codes, and service line specifics.
Billing Code Overview
CPT code 0445U is a Proprietary Laboratory Analyses (PLA) code that applies exclusively to the Elecsys® Phospho–Tau (181P) CSF (pTau181) and β–Amyloid (1–42) CSF II (Abeta 42) Ratio test produced by Roche Diagnostics Operations Inc. The assay uses cerebrospinal fluid and an electrochemiluminescent immunoassay (ECLIA) method to generate a pTau181/Abeta42 ratio value that may assist clinicians evaluating patients with signs of cognitive impairment.
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Service type: Clinical laboratory test — cerebrospinal fluid biomarker assay
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Typical site of service: Inpatient or outpatient clinical laboratory settings where cerebrospinal fluid specimens are collected and analyzed
Clinical & Coding Specifications
Clinical Context
A 68-year-old patient presents to a neurology clinic with progressive memory loss and word-finding difficulty over 18 months. The neurologist documents objective cognitive impairment on bedside testing and orders cerebrospinal fluid (CSF) biomarkers to support differential diagnosis between Alzheimer disease and other causes of cognitive decline. A lumbar puncture is performed in an outpatient or hospital ambulatory procedure room; CSF is sent to a reference lab. Laboratory personnel run the proprietary Elecsys® assays from Roche Diagnostics on the CSF sample to generate the pTau181/Abeta42 ratio reported under CPT code 0445U. Results are returned to the ordering clinician to inform diagnostic decision‑making alongside clinical exam, neuroimaging, and neuropsychological testing. Typical sites of service include hospital outpatient departments, ambulatory surgical centers, and reference laboratories performing Proprietary Laboratory Analyses.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the professional interpretation component if applicable (e.g., pathologist interpretation billed separately). |