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The ADVIA® Centaur Intact Parathyroid (iPTH) assay is for in vitro diagnostic use in the quantitative determination of intact parathyroid hormone (iPTH) in EDTA plasma or serum using the ADVIA Centaur XP system. This assay is intended to be used to aid in the differential diagnosis of hyperparathyroidism and hypoparathyroidism.

The ADVIA Centaur iPTH assay is a two-site sandwich immunoassay using direct chemiluminometric technology, which uses constant amounts of an antihuman PTH antibody in the Lite Reagent and an antihuman PTH antibody in the Solid Phase Reagent. The first antibody is a polyclonal goat antihuman PTH (N-terminal 1-34) antibody labeled with acridinium ester. The second antibody is a biotinylated polyclonal goat antihuman PTH (39-84 region) antibody that is preformed to streptavidin coated paramagnetic latex particles in the Solid Phase reagent.

The ADVIA Centaur iPTH reagent kit contains the following:
. ReadyPack® primary reagent pack containing ADVIA Centaur Lite and Solid Phase Reagent)
ADVIA Centaur iPTH Master Curve card .

Materials Required but Not Provided
iPTH Calibrator .
Optional Reagents
ADVIA Centaur Multi-Diluent 11 .
iPTH 1, 2, 3 quality control material .
iPTH Master Curve Material .

The Siemens ADVIA® Centaur Intact Parathyroid (iPTH) Assay is a quantitative in vitro diagnostic device used to measure intact parathyroid hormone (iPTH) in EDTA plasma or serum to aid in the differential diagnosis of hyperparathyroidism and hypoparathyroidism. The device's performance was evaluated through studies on precision, interfering substances, cross-reactivity, and method comparison, demonstrating substantial equivalence to the predicate device, the Abbott Architect Intact PTH assay.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria were implicitly established by demonstrating comparability to the predicate device and meeting common analytical performance standards for in vitro diagnostic assays. The specific acceptance thresholds for each performance characteristic (e.g., %CV for precision, % bias for interference) are not explicitly stated as numbered criteria but are inferred from the reported results and the conclusion of substantial equivalence.

*   **Data Provenance:** Not explicitly stated, but typically involves collecting samples from a healthy population, likely prospective.

3. Number of Experts and Qualifications

This submission pertains to an in vitro diagnostic assay, which relies on quantitative measurements rather than expert interpretation of images or clinical findings. Therefore, the concept of "experts" to establish ground truth in the context of diagnostic imaging or clinical assessment is not applicable here. The ground truth is based on the chemical and immunological properties of the assay and comparison to a legally marketed predicate device.

4. Adjudication Method

Not applicable for an in vitro diagnostic assay like this. Adjudication methods are typically used in studies involving human interpretation or subjective assessments (e.g., by multiple readers).

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

Not applicable. This is an in vitro diagnostic assay, not a device requiring human reader interpretation or assistance.

6. Standalone Performance

Yes, the studies described are for the standalone performance of the ADVIA Centaur iPTH assay (algorithm only, without human-in-the-loop performance in the sense of interpretative assistance). The performance metrics (precision, interference, cross-reactivity, method comparison) directly evaluate the assay's ability to accurately and reliably measure iPTH concentrations.

7. Type of Ground Truth Used

The ground truth for this device is established primarily by:

• Quantitative Chemical Measurement: The assay directly measures the concentration of intact parathyroid hormone using a chemiluminescent immunoassay. The "truth" is the actual concentration of iPTH in the samples.
• Comparison to a Predicate Device: For method comparison, the results from the legally marketed Abbott Architect Intact PTH assay (K063232) served as the reference or "ground truth" to establish substantial equivalence.
• Known Reference Standards/Spiked Samples: For precision and interference studies, the ground truth is often established by using clinically relevant pools with known or spiked analyte concentrations.
• Clinically Established Reference Ranges: Normal physiological ranges for iPTH from healthy donors are used to establish expected values.

8. Sample Size for the Training Set

The provided summary does not explicitly mention a "training set" in the context of machine learning or AI models. This device is a traditional immunoassay, which does not typically involve distinct training and test sets in the same way an AI/ML device would. The development (optimization and calibration) of the assay itself would involve numerous samples, but these are part of the assay's development and validation, not a formal "training set" as described in AI. The "testing" samples mentioned above are for performance validation for regulatory submission.

9. How the Ground Truth for the Training Set was Established

As noted above, the concept of a formal "training set" with established ground truth is not directly applicable to this traditional immunoassay. The development and optimization of such assays involve:

• Biochemical assays and calibration curves: These define the relationship between the signal detected (Relative Light Units) and the analyte concentration (iPTH). This is established using known iPTH standards.
• Cross-validation and optimization: During development, various reagents and parameters are tested and optimized using a wide range of samples to ensure robust and accurate performance across the assay's range.
• Reference materials and spiked samples: These are used to ensure the assay can accurately quantify iPTH across different concentrations and in the presence of potential interferences.

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