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The LIAISON® N-TACT® PTH Gen II is an in vitro chemiluminescent immunoassay (CLIA) intended for the quantitative determination of intact human parathyroid hormone in serum, EDTA and Lithium Heparin plasma samples. Measurements of parathyroid hormone levels are used in the differential diagnosis of hypercalcemia and hypocalcemia resulting from disorders of calcium metabolism. The test is to be performed on the LIAISON® XL Analyzer.

The LIAISON® N-TACT® PTH Gen II Control Set is intended for use as assayed quality control samples to monitor the accuracy and precision of the DiaSorin LIAISON® N-TACT® PTH Gen II assay.

The LIAISON® N-TACT® PTH Gen II Calibration Verifiers are assayed quality control materials intended for the quantitative verification of calibration and reportable range of the LIAISON® N-TACT® PTH Gen II assay.

The LIAISON® N-TACT® PTH Gen II assay is a modified two-step, two-site sandwich assay that uses two goat polyclonal antibodies for capture and detection of intact PTH. Results are determined by a 2 point calibration conversion of the master curve to a working curve. The light signal is measured by a photomultiplier as relative light units (RLU) and is proportional to the concentration of intact PTH present in the calibrators, controls or samples.

LIAISON® N-TACT® PTH Gen II Control set contains:
2 levels controls containing 80% human plasma spiked with 1-84 PTH, and preservatives; 4 vials each level; lyophilized
The target concentration for control level 1 is 20 pg/mL. The target concentration for control Level 2 is 300 pg/mL.
The range of concentrations of each control is reported on the certificate of analysis provided with each LIAISON® N-TACT® PTH Gen II Control set.

LIAISON® N-TACT® PTH Gen II Calibration Verifier set contains:
4 levels containing 80% human plasma spiked with 1-84 PTH, with preservative, . 1 vial each level, lyophilized
The target concentration for cal verifier A is 10 pg/mL. The target concentration for cal verifier B is 150 pg/mL. The target concentration for cal verifier C is 650 pg/mL. The target concentration for cal verifier D is 1600 pg/mL.
The range of concentrations of each calibration verifier is reported on the certificate of analysis provided with each LIAISON® N-TACT® PTH Gen II Calibration Verifier set.

Here's an analysis of the acceptance criteria and study details for the LIAISON® N-TACT® PTH Gen II device based on the provided 510(k) summary:

Acceptance Criteria and Reported Device Performance

The 510(k) summary for the LIAISON® N-TACT® PTH Gen II primarily demonstrates substantial equivalence to a predicate device. As such, the "acceptance criteria" are generally implied by the performance of the predicate device and the demonstration that the new device performs comparably or better, meeting established clinical laboratory guidelines. Specific numeric acceptance criteria are not explicitly stated in a "PASS/FAIL" format for each performance characteristic, but rather the study results are presented to show satisfactory performance.

Here's a table summarizing the performance characteristics and their reported results, which implicitly serve as the demonstration of meeting acceptance:

Study Details for LIAISON® N-TACT® PTH Gen II

1. Sample sizes used for the test set and data provenance:

   • Method Comparison: 198 patient samples. The provenance is not explicitly stated as country of origin, but the reference range study mentions "northern and southern regions of the U.S.", suggesting US-based samples for some studies. The study is retrospective, utilizing existing patient samples.
   • Sample Matrix Comparison: 65 matched patient sets (EDTA plasma, serum, SST serum, and Lithium Heparin plasma). Data provenance is not explicitly stated beyond being "patient sets." Retrospective.
   • Reference Range: 125 apparently healthy adults aged 21-70 years from mixed ethnic backgrounds (32.5% dark-skinned, 66.7% light-skinned, 0.8% unknown) from the northern and southern regions of the U.S. This is a prospective or retrospective collection of samples for establishing a reference interval.
   • Precision: 7 frozen EDTA plasma samples (coded panel) and 2 lots of LIAISON® N-TACT® PTH Gen II controls (2 levels). Samples were tested on two lots of reagents. This is a controlled lab study, not involving patient data per se beyond the initial source of the plasma samples.
   • Linearity: One sample pool of each type: serum, SST serum, EDTA plasma, and Lithium Heparin plasma. These were diluted. Controlled lab study.
   • High Dose Hook Effect: A zero sample spiked with PTH. Controlled lab study.
   • Recovery Study: 5 high concentration EDTA plasma samples and 5 low concentration EDTA plasma samples. Controlled lab study, not directly patient data.
   • Analytical Specificity (Cross-Reactivity & Interference): Samples spiked with specific substances. These are controlled lab studies.
   • Limit of Blank, Limit of Detection, Limit of Quantitation: Not explicitly stated, usually involves multiple replicates of blank and low-concentration samples. Controlled lab study.

2. Number of experts used to establish the ground truth for the test set and qualifications of those experts:

   • This device is an in vitro diagnostic (IVD) immunoassay, not an image-based AI device. The "ground truth" is established through analytical methods and comparison to established, cleared diagnostic devices (predicate device) and clinical standards, rather than expert human interpretation.
   • For the method comparison, the "ground truth" for the test set is the result from the predicate device, Siemens ADVIA® CENTAUR INTACT Parathyroid Hormone (iPTH) Assay, which is an FDA-cleared device.
   • For other analytical performance studies (precision, linearity, recovery, etc.), the ground truth relies on carefully prepared samples with known concentrations or expected behaviors, measured against established analytical principles and validated laboratory methods. There are no "experts" establishing image-based ground truth here.

3. Adjudication method for the test set:

   • Not applicable as this is an IVD immunoassay, not a diagnostic imaging AI where human adjudication of ambiguous cases is typically required. The comparison is objective, numerical data between two analytical methods or against defined analytical targets.

4. If a multi-reader multi-case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance:

   • Not applicable. This is an IVD assay, not an AI-powered diagnostic imaging tool that assists human readers. The performance is assessed against a predicate device and analytical standards.

5. If a standalone (i.e., algorithm only without human-in-the-loop performance) was done:

   • The LIAISON® N-TACT® PTH Gen II assay is a standalone device in the sense that it provides quantitative results for PTH concentration. It operates autonomously on the LIAISON® XL Analyzer without direct human interpretation of the result generation process. Interpretation of the PTH level in a clinical context (e.g., diagnosis of hyper/hypocalcemia) still involves human clinicians, but the device provides the raw measurement itself without human input into the measurement.

6. The type of ground truth used:

   • For Method Comparison: Results from the predicate device (Siemens ADVIA® CENTAUR INTACT PTH (iPTH) Assay, K020217).
   • For other analytical studies (Precision, Linearity, Recovery, etc.): Typically based on known concentrations of analytes in spiked samples or reference materials, or expected analytical behaviors according to established CLSI guidelines (e.g., EP5-A2 for Precision, EP6-A for Linearity, EP7-A2 for Interference, EP17-A2 for Detection Capability). For the reference range, it's derived from a healthy population cohort carefully selected using specific clinical criteria.

7. The sample size for the training set:

   • This document describes performance characteristics for an IVD kit, not an AI/Machine Learning model. Therefore, there isn't a "training set" in the sense of data used to train an algorithm. The development of the assay itself would involve internal optimization and validation, but these stages are not typically referred to as "training sets" in the context of conventional IVDs in 510(k) summaries.

8. How the ground truth for the training set was established:

   • As there is no "training set" in the AI/ML context, this question is not applicable. The assay's analytical characteristics are developed and verified through standard laboratory practices and comparison to reference methods, not through an iterative learning process with labeled data.

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