CPT® Code 84394

1. Indications

The total tau (tTau) test, represented by CPT® Code 84394, is indicated for the assessment of neurodegenerative conditions, particularly Alzheimer's disease. The following conditions and symptoms may warrant the use of this test:

• Alzheimer’s Disease Diagnosis The test is utilized to support the diagnosis of Alzheimer's disease by measuring the levels of total tau protein in the blood, which correlates with the presence of neurofibrillary tangles in the brain.
• Differentiation of Dementia Types The tTau test can assist in distinguishing Alzheimer's disease from other forms of dementia, particularly frontotemporal lobe degenerative diseases, by evaluating tau protein levels.
• Monitoring Disease Progression The test may be used to monitor the progression of Alzheimer's disease and the effectiveness of therapeutic interventions over time.

2. Procedure

The procedure for conducting the total tau (tTau) test involves several key steps to ensure accurate measurement of tau protein levels in the blood. The following procedural steps are outlined:

• Step 1: Sample Collection A blood sample is collected from the patient, typically via venipuncture. It is crucial that the sample is handled properly to maintain the integrity of the proteins being measured.
• Step 2: Sample Preparation The collected blood sample is processed to separate the plasma or serum, which contains the tau proteins. This step is essential for accurate testing, as it removes cellular components that could interfere with the assay.
• Step 3: Assay Testing The prepared sample undergoes testing using electrochemiluminescence-based assays. This method is sensitive and allows for the quantification of total tau protein levels in the sample.
• Step 4: Result Interpretation The results of the assay are analyzed, and the total tau levels are reported. Elevated levels of tTau may indicate the presence of neurofibrillary tangles associated with Alzheimer's disease.

3. Post-Procedure

After the total tau (tTau) test is completed, the patient may experience no significant post-procedure care requirements, as the blood draw is a routine procedure. However, it is important to monitor the patient for any immediate adverse reactions to the venipuncture, such as bruising or discomfort at the site. The results of the tTau test should be discussed with the patient in the context of their overall clinical picture, and further diagnostic or therapeutic steps may be determined based on the findings. Follow-up appointments may be necessary to review the results and consider additional testing or interventions as needed.