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.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare0445UCPTProprietary Laboratory AnalysesCSF biomarkerspTau181Abeta42electrochemiluminescent immunoassayneurologyAlzheimer's biomarkers

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.

Service type: Clinical laboratory test — cerebrospinal fluid biomarker assay
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).
`TC`	Technical component	Use when billing only the technical component for the laboratory assay performed by the facility.
`52`	Reduced services	Use when the test was partially performed or specimen insufficient for full analysis but a reduced service was completed.
`53`	Discontinued procedure	Use when testing was started but discontinued for reasons not related to patient refusal.
`59`	Distinct procedural service	Not listed in the provided modifiers; not used.
`QX`	CLIA modifier: qualified non‑physician	Use when the performing laboratory professional meets CLIA requirements and billing requires a modifier indicating a laboratory professional provided the test.
`QK`	CLIA modifier: high complexity personnel	Use when high‑complexity testing personnel performed the assay and payer requires the CLIA personnel modifier.
`QY`	CLIA modifier: advanced practice provider	Use when an advanced practice provider is involved in ordering/performing aspects that require this modifier per payer rules.
`CO`	Cost containment organization	Use when services are provided under a workers’ compensation or cost-containing program that requires this modifier.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery	Use only if applicable per payer rules when such a clinician assists during lumbar puncture or procedural components.
`23`	Unusual anesthesia	Use when unusual anesthesia is required for lumbar puncture related to specimen collection.
`78`	Unplanned return to the operating/procedure room	Use if a patient requires an unplanned return for repeat lumbar puncture within the global period.
`80`	Assistant surgeon	Use if an assistant surgeon is billed for the invasive procedure component (lumbar puncture) when payer allows.

Taxonomy Code	Specialty	Notes
2084P0800X	Neurology	Ordering and interpreting clinicians for cognitive disorders.
207RH0000X	Pathology	Laboratory oversight and interpretation of CSF biomarker assays.
261QM0800X	Clinical Laboratory	Laboratory professionals performing high‑complexity immunoassays.
208D00000X	Family Medicine	Primary care clinicians who may order CSF biomarkers in diagnostic workup.
363L00000X	Radiology (Diagnostic)	Often involved in imaging correlation though not performing the assay.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`G30.9`	Alzheimer disease, unspecified	Most common diagnosis for which CSF `pTau181/Abeta42` ratio aids diagnostic evaluation.
`F02.80`	Dementia in other diseases classified elsewhere without behavioral disturbance	Dementia of non‑Alzheimer or mixed etiologies where biomarkers help distinguish underlying pathology.
`F03.90`	Unspecified dementia, without behavioral disturbance	Used when cognitive decline is documented but etiology is not yet determined; CSF biomarkers assist workup.
`G31.84`	Mild cognitive impairment, so stated	Early cognitive changes where CSF biomarker ratios can support risk stratification for Alzheimer disease.
`R41.3`	Other amnesia	Amnestic presentations prompting CSF biomarker testing to evaluate Alzheimer‑related pathology.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`62270`	Spinal puncture, lumbar, diagnostic	Performed to obtain cerebrospinal fluid for the Elecsys® CSF biomarker test; typically performed immediately before sending the sample for `0445U`.
`36415`	Collection of venous blood by venipuncture	May be performed for concurrent serum testing when paired serum/CSF comparisons or safety labs are required.
`81002`	Urinalysis, by dipstick or tablet reagent; non-automated, without microscopy	May be ordered as part of pre-procedure screening prior to lumbar puncture in ambulatory settings.
`88305`	Level IV pathology, gross and microscopic examination	Used when neuropathology or additional CSF cytology is performed alongside biomarker testing.
`80502`	Creatine kinase; MB isoenzyme (CK-MB)	Not directly related; include only if cardiac workup coincidentally performed.

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Summary & Overview

CPT 0445U: Elecsys pTau181/Abeta42 CSF Ratio Assay

Data not available in the input for associated taxonomies, ICD-10 diagnoses, related codes, and service line specifics.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare0445UCPTProprietary Laboratory AnalysesCSF biomarkerspTau181Abeta42electrochemiluminescent immunoassayneurologyAlzheimer's biomarkers

Billing Code Overview

Service type: Clinical laboratory test — cerebrospinal fluid biomarker assay
Typical site of service: Inpatient or outpatient clinical laboratory settings where cerebrospinal fluid specimens are collected and analyzed

Clinical & Coding Specifications

Clinical Context

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).
`TC`	Technical component	Use when billing only the technical component for the laboratory assay performed by the facility.
`52`	Reduced services	Use when the test was partially performed or specimen insufficient for full analysis but a reduced service was completed.
`53`	Discontinued procedure	Use when testing was started but discontinued for reasons not related to patient refusal.
`59`	Distinct procedural service	Not listed in the provided modifiers; not used.
`QX`	CLIA modifier: qualified non‑physician	Use when the performing laboratory professional meets CLIA requirements and billing requires a modifier indicating a laboratory professional provided the test.
`QK`	CLIA modifier: high complexity personnel	Use when high‑complexity testing personnel performed the assay and payer requires the CLIA personnel modifier.
`QY`	CLIA modifier: advanced practice provider	Use when an advanced practice provider is involved in ordering/performing aspects that require this modifier per payer rules.
`CO`	Cost containment organization	Use when services are provided under a workers’ compensation or cost-containing program that requires this modifier.
`AS`	Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery	Use only if applicable per payer rules when such a clinician assists during lumbar puncture or procedural components.
`23`	Unusual anesthesia	Use when unusual anesthesia is required for lumbar puncture related to specimen collection.
`78`	Unplanned return to the operating/procedure room	Use if a patient requires an unplanned return for repeat lumbar puncture within the global period.
`80`	Assistant surgeon	Use if an assistant surgeon is billed for the invasive procedure component (lumbar puncture) when payer allows.

Taxonomy Code	Specialty	Notes
2084P0800X	Neurology	Ordering and interpreting clinicians for cognitive disorders.
207RH0000X	Pathology	Laboratory oversight and interpretation of CSF biomarker assays.
261QM0800X	Clinical Laboratory	Laboratory professionals performing high‑complexity immunoassays.
208D00000X	Family Medicine	Primary care clinicians who may order CSF biomarkers in diagnostic workup.
363L00000X	Radiology (Diagnostic)	Often involved in imaging correlation though not performing the assay.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`G30.9`	Alzheimer disease, unspecified	Most common diagnosis for which CSF `pTau181/Abeta42` ratio aids diagnostic evaluation.
`F02.80`	Dementia in other diseases classified elsewhere without behavioral disturbance	Dementia of non‑Alzheimer or mixed etiologies where biomarkers help distinguish underlying pathology.
`F03.90`	Unspecified dementia, without behavioral disturbance	Used when cognitive decline is documented but etiology is not yet determined; CSF biomarkers assist workup.
`G31.84`	Mild cognitive impairment, so stated	Early cognitive changes where CSF biomarker ratios can support risk stratification for Alzheimer disease.
`R41.3`	Other amnesia	Amnestic presentations prompting CSF biomarker testing to evaluate Alzheimer‑related pathology.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`62270`	Spinal puncture, lumbar, diagnostic	Performed to obtain cerebrospinal fluid for the Elecsys® CSF biomarker test; typically performed immediately before sending the sample for `0445U`.
`36415`	Collection of venous blood by venipuncture	May be performed for concurrent serum testing when paired serum/CSF comparisons or safety labs are required.
`81002`	Urinalysis, by dipstick or tablet reagent; non-automated, without microscopy	May be ordered as part of pre-procedure screening prior to lumbar puncture in ambulatory settings.
`88305`	Level IV pathology, gross and microscopic examination	Used when neuropathology or additional CSF cytology is performed alongside biomarker testing.
`80502`	Creatine kinase; MB isoenzyme (CK-MB)	Not directly related; include only if cardiac workup coincidentally performed.