Summary & Overview
CPT 0035U: RT–QuIC Prion Detection in Cerebrospinal Fluid
CPT code 0035U identifies a proprietary laboratory test: real–time quaking–induced conversion (RT–QuIC) for detection of abnormal prion proteins in cerebrospinal fluid. This PLA code is specific to the National Prion Disease Pathology Surveillance Center and reports a qualitative result to aid diagnosis of prion disease. Nationally, the code represents a highly specialized diagnostic service used in suspected prion disease cases where conventional assays are insufficient.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The discussion examines payer coverage patterns, typical clinical contexts for test ordering, and how reporting a PLA code differs from more widely used laboratory codes.
Readers will learn the clinical purpose of the assay, typical site-of-service expectations, and the implications of the code being a PLA (provider- or manufacturer-specific) for billing and claims reporting. The publication also outlines policy-relevant considerations for payers and providers, including how a single-source PLA code can affect claim adjudication and documentation expectations. Data not available in the input for associated taxonomies, ICD-10 mappings, and related procedure codes are noted where applicable.
Billing Code Overview
CPT code 0035U is a Proprietary Laboratory Analyses (PLA) code for real–time quaking–induced conversion (RT–QuIC) for prion detection performed by the National Prion Disease Pathology Surveillance Center. The test detects abnormal prion proteins in cerebrospinal fluid (CSF) and yields a qualitative result (positive or negative) to aid in the diagnosis of prion disease.
-
Service type: Specialized laboratory diagnostic testing using RT–QuIC methodology
-
Typical site of service: Reference or specialized clinical laboratory (laboratory testing on CSF specimens)
Data not available in the input for modifiers, associated taxonomies, ICD-10 diagnoses, related codes, and service line.
Clinical & Coding Specifications
Clinical Context
A 62-year-old patient presents to a neurology clinic with rapidly progressive dementia, new-onset myoclonus, and cerebellar dysfunction over several weeks. The neurologist obtains neuroimaging and standard laboratory testing that are inconclusive for infectious, metabolic, or autoimmune causes. Cerebrospinal fluid (CSF) is obtained by lumbar puncture in the hospital or outpatient infusion/ambulatory surgery center and sent to the National Prion Disease Pathology Surveillance Center for specialized testing. The laboratory performs real–time quaking–induced conversion (RT–QuIC) on the CSF sample and returns a qualitative result (positive or negative) to aid in the diagnosis of prion disease. Typical workflow steps include CSF collection with appropriate labeling and chain-of-custody, shipping to the reference center under required conditions, receipt and processing by the reference lab, performance of RT–QuIC, and reporting of the qualitative result to the ordering clinician for integration with clinical, radiologic, and electroencephalographic findings.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
26 | Professional component | Use when reporting only the professional interpretation component if separate technical and professional components apply and are billed separately. |
| 52 | Reduced services | Use when the laboratory procedure is partially reduced or not fully performed for clinical reasons.
| 53 | Discontinued procedure | Use when the test was started but discontinued due to patient-related or specimen issues.
| 54 | Surgical care only | Rarely applicable; use if another provider is billing the procedural specimen collection and this lab bills only the analysis (use cautiously with payer rules).
| 55 | Postoperative management only | Uncommon for this test; include only if clinically indicated under specific billing arrangements.
| 62 | Two surgeons | Use only when two qualified providers are sharing responsibility for specimen collection under specific circumstances.
| 78 | Unplanned return to the operating/procedure room | Use if an unplanned repeat lumbar puncture in the operating/procedure room is required and reported separately.
| 80 | Assistant at surgery | Use if an assistant is involved in the specimen collection procedure and billing permits reporting of assistant services.
| 82 | Assistant at surgery (when qualified resident not available) | Use when an assistant provides services in absence of a qualified resident.
| AD | Advanced diagnostic imaging component | Use if advanced imaging components are separately billable in an associated workflow (rare for this lab test).
| QX | Services performed by an assistant surgeon (CRNA/PA/NP) | Use when applicable under payer policy for assistant-provided specimen collection.
| QY | Services performed by a registered nurse anesthetist | Use if applicable in the procedural setting where anesthesia services are billed separately.
| TC | Technical component | Use when billing only the laboratory technical component (most common for reference lab reporting of RT–QuIC).
| SH | Diagnostic tests ordered by another provider | Use when this lab test is ordered by a different provider than the one submitting the claim.
| Taxonomy Code | Specialty | Notes |
|---|---|---|
2084P0400X | Neurology | Ordering clinicians commonly include neurologists evaluating rapidly progressive dementia. |
| 207Q00000X | Pathology | Pathologists at reference labs oversee performance and interpretation of specialized CSF assays.
| 363L00000X | Clinical Laboratory | Clinical laboratory directors and technologists at the reference center perform the RT–QuIC assay.
| 208000000X | Radiology (Neuroradiology) | Neuroradiologists frequently participate in the diagnostic workflow with MRI that complements CSF testing.
| 207K00000X | Infectious Disease | Infectious disease specialists may be involved in differential diagnosis when infectious causes are considered.
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
A81.0 | Creutzfeldt-Jakob disease | Primary prion disease diagnosis; RT–QuIC is used to detect abnormal prion protein to support this diagnosis. |
| F02.80 | Dementia in other diseases classified elsewhere without behavioral disturbance | Used when dementia is present and prion disease is being considered in the differential.
| G31.84 | Mild cognitive impairment, so stated | Early cognitive decline assessment; RT–QuIC may be used when progression suggests prion disease.
| R41.3 | Other amnesia | Cognitive symptoms such as amnesia may prompt CSF evaluation including prion testing.
| R56.9 | Unspecified convulsions | New-onset myoclonus or seizure activity in the context of rapidly progressive dementia may prompt testing.
| G93.4 | Encephalopathy, unspecified | When encephalopathic processes are unexplained and prion disease is in the differential, RT–QuIC may be ordered.
| G31.9 | Degenerative disease of nervous system, unspecified | Broad code used during workup when specific degenerative diagnosis is pending and RT–QuIC is considered.
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
0035U | Real-time quaking-induced conversion (RT–QuIC) for prion detection, qualitative; specific to National Prion Disease Pathology Surveillance Center | Primary PLA code for the specialized CSF assay performed on the sample sent to the reference center. |
| 62270 | Spinal puncture, lumbar, diagnostic | Performed to obtain CSF specimen for RT–QuIC testing; typically performed prior to sending sample to the reference lab.
| 36415 | Collection of venous blood by venipuncture | May be performed for concomitant serologic or laboratory testing in the diagnostic workup.
| 99000 | Handling and/or conveyance of specimen(s) for transfer from site of collection to another facility or lab | Used when specimens require special handling/transport to the reference laboratory (check payer policy).
| 88305 | Surgical pathology, gross and microscopic examination | May be used when brain biopsy tissue is submitted for histopathology in rare cases alongside CSF testing.
| 86850 | Infectious agent antigen detection by immunoassay technique | Represents other specialized infectious disease assays that may be ordered in parallel; not specific to prion testing.