Interpace ThyraMIR FNA Pass Requirements
For Interpace ThyraMIR testing of thyroid nodules, a minimum of 2 dedicated FNA passes should be obtained, though 3-4 passes are recommended to optimize specimen adequacy and molecular testing success.
Specimen Requirements for Molecular Testing
The available evidence does not provide specific manufacturer guidelines for ThyraMIR pass requirements in the provided materials. However, thyroid FNA molecular testing requirements can be extrapolated from general thyroid FNA best practices and molecular testing studies:
Minimum Pass Recommendations
- Without on-site adequacy assessment: Perform at least 3 needle passes per thyroid nodule to maximize diagnostic adequacy 1, 2
- With rapid on-site adequacy assessment (ROSAA): The number of passes can be adjusted based on real-time cytology evaluation, with studies showing mean passes of 3.2-3.8 achieving adequate specimens 1, 2
Evidence Supporting Pass Numbers
- Studies of thyroid FNA demonstrate that adequacy rates improve with increasing passes: specimen adequacy reaches 90.1% after the first pass, 98.1% after two passes, and approaches 100% after three passes 3
- One study specifically evaluating molecular testing (ThyGenX/ThyraMIR) at an institution showed successful risk stratification, though the specific number of passes dedicated to molecular testing was not explicitly stated 4
- The mean number of needle punctures necessary for adequate thyroid specimens ranges from 3.2 to 5.4 depending on operator experience and technique 1
Practical Approach
Standard Protocol
- Perform 3-4 total FNA passes for thyroid nodules requiring molecular testing 1, 2
- Dedicate at least 2 passes specifically for molecular analysis if splitting samples between cytology and molecular testing 5
- If ROSAA is available, use it to confirm adequacy and potentially reduce unnecessary passes 1, 2
Factors Affecting Adequacy
- Nodule characteristics: Cystic nodules have significantly higher inadequacy rates (15%) compared to solid nodules (1%) and may require additional passes 1
- Increased intranodular vascularization: Associated with lower diagnostic yield (51.8% adequacy) and may necessitate additional passes 2
- Operator experience: Less experienced operators may require more passes to achieve adequate specimens 1
Important Caveats
- The specific manufacturer requirements for ThyraMIR should be confirmed directly with Interpace Diagnostics, as commercial molecular tests may have proprietary specimen requirements not detailed in published literature
- Contact the processing laboratory before the procedure to confirm their specific collection requirements, including number of passes, collection media, and handling protocols 5
- Consider performing one additional pass beyond the minimum if the nodule has challenging characteristics (cystic, highly vascular, or small size <1 cm) 1, 2, 6