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The CPT® Code 84393 refers to the testing of phosphorylated tau proteins, specifically pTau 181 and pTau 217, which are critical biomarkers in the assessment of Alzheimer’s disease. Neurofibrillary tangles, which are formed by the abnormal accumulation of tau protein in the brain, represent one of the two primary neuropathological features associated with Alzheimer’s disease. These tangles develop within neurons as a result of the hyperphosphorylation of tau, a process that typically occurs following the formation of beta-amyloid plaques, the first hallmark of the disease. Notably, the pathological build-up of hyperphosphorylated tau can begin 10 to 15 years prior to the onset of clinical symptoms, indicating its potential role in early diagnosis. Among the tau proteins, pTau 217 has emerged as a more recent and promising blood-based marker. An elevated level of pTau 217 is indicative of the neuropathological changes characteristic of Alzheimer’s disease. While both pTau 181 and pTau 217 levels are elevated in individuals with clinical Alzheimer’s, pTau 217 may offer superior differentiation between Alzheimer’s disease and other frontotemporal lobe degenerative disorders, as it is a more robust indicator of amyloid activity and tau binding observed in the temporal cortex through PET imaging. The testing for these proteins is conducted using electrochemiluminescence-based assays, and the appropriate CPT® code for each protein tested is 84393, while the total tau test is reported under code 84394.
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The testing for phosphorylated tau proteins, specifically pTau 181 and pTau 217, is indicated for the evaluation of Alzheimer’s disease and related neurodegenerative conditions. The following conditions may warrant this testing:
The procedure for testing phosphorylated tau proteins involves several key steps, which are outlined below:
After the procedure, patients may not require any specific post-procedure care, as blood sampling is a minimally invasive process. However, it is essential to monitor the patient for any immediate adverse reactions to the blood draw, such as bruising or discomfort at the puncture site. The results of the phosphorylated tau protein tests will typically be available within a specified timeframe, depending on the laboratory's processing capabilities. Clinicians should follow up with patients to discuss the results and any further diagnostic or therapeutic steps that may be necessary based on the findings.
| Short Descr | TAU PHOSPHORYLATED EA | Medium Descr | TAU PHOSPHORYLATED EACH | Long Descr | Tau, phosphorylated (eg, pTau 181, pTau 217), each | Status Code | Statutory Exclusion (from MPFS, may be paid under other methodologies) | Global Days | XXX - Global Concept Does Not Apply | PC/TC Indicator (26, TC) | 9 - Not Applicable | Multiple Procedures (51) | 9 - Concept does not apply. | Bilateral Surgery (50) | 9 - Concept does not apply. | Physician Supervisions | 09 - Concept does not apply. | Assistant Surgeon (80, 82) | 9 - Concept does not apply. | Co-Surgeons (62) | 9 - Concept does not apply. | Team Surgery (66) | 9 - Concept does not apply. | Diagnostic Imaging Family | 99 - Concept Does Not Apply | CLIA Waived (QW) | No | APC Status Indicator | Conditionally packaged laboratory tests | Type of Service (TOS) | 5 - Diagnostic Laboratory | Berenson-Eggers TOS (BETOS) | none | MUE | Not applicable/unspecified. |
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| 2025-01-01 | Added | Code Added. |
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