| 14-3-3γ (ELISA), Total TAU (ELISA) and RT-QuIC for Prion Proteins | |
|---|---|
| CPT Code | 86317 (14-3-3 & TAU), 0035U (RT-QuIC) |
| Ordering Recommendation |
May aid in the diagnosis of prion disease. RT-QuIC identifies the disease-causing agent. Total TAU and 14-3-3γ are indirect markers of neurodegenerative diseases. |
| Methodology | Quantitative Enzyme-Linked Immunosorbent Assay (ELISA). Real-Time Quaking-Induced Conversion (RT-QuIC)ii. |
| Available STAT | No. |
| Analytic Timeiii | 7 business days. |
| Submit With Order | NPDPSC CSF Test Requisition Form |
| Specimen Requirements | |
|---|---|
| Patient preparation | The patient must be 12 years of age or older. |
| Specimen Type | Cerebrospinal Fluid (CSF) obtained by lumbar puncture. |
| Preferred Container | SARSTEDT Polypropylene (PP), low binding, sterile collection tube (Cat. No. 63.614.625) |
| Specimen Preparation | The first 2ml of CSF that flows from the tap should be discarded. Collect 2 ml of CSF (1 ml minimum), avoiding bloody tap. The sample must be immediately frozen, at least in a -20°C freezer. |
| Storage/Transport Temperature |
Frozen. Shipping transport on dry ice.iv. Please note: shipments are not received on weekends and/or holidays. Ship only Monday through Thursday (priority overnight). |
| Unacceptable Conditions | Bloody and insufficient sample quantity. Samples that are colored or contain blood cannot be performed for RT-QuIC and 14-3-3 GAMMA. |
| Remarks | Complete the required test request form linked above. |
| Stability | Freeze CSF at -20°C immediately after collection. |
| Specimen Reporting | |
|---|---|
| Critical Results | None. |
| Reference Range(s) | RT-QuIC: Negative Total TAU (ELISA): 0-1149 pg/mL 14-3-3 GAMMA (ELISA): 173 - 1999 AU/mL. |
| Likelihood of Prion Disease | RT-QuIC Positive: >98% RT-QuIC Negative & Total TAU <499 = <0.2% RT-QuIC Negative & Total TAU 500-2499 = <1% |
References
i. Conditions include but are not limited to, subarachnoid hemorrhage, various encephalitis, stroke with acute infarction, multi-infarct dementia with acute infarction, brain neoplasm, and paraenoplastic neurological disorders. These conditions may yield false-positive results.
ii. CSF RT-QuIC has a diagnostic sensitivity and specificity of 90.3% and 98.5%, respectively (Rhoads DD, Neurology 2020).
iii. Expected turnaround time (business days) for results, beginning when the center receives the specimen.
iv. A recent re-evaluation of the shipment conditions of CSF specimens showed that shipment at room temperature caused a decrease in the accuracy of RT-QuIC, 14-3-3 protein, and TAU protein assays when compared with the shipment of frozen CSF samples on dry ice.