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The TSHL method is an in vitro diagnostic test for the quantitative measurement of Thyroid Stimulating Hormone (TSH, thyrotropin) in human serum and plasma on the Dimension® EXL™ integrated chemistry system with LOCI® Module. Measurements of TSH are used in the diagnosis and monitoring of thyroid disease.

The FT4L method is an in vitro diagnostic test for the quantitative measurement of Free Thyroxine in human serum and plasma on the Dimension® EXL™ integrated chemistry system with LOCI® Module. Measurements of free thyroxine are used in the diagnosis and monitoring of thyroid disease.

The Dimension® LOCI® Thyroid Stimulating Hormone Flex® reagent cartridge (TSHL) and Dimension® LOCI® Free Thyroxine Flex® reagent cartridge (FT4L) assays were cleared under K081074 and K073604, respectively. The components of the cleared assays were modified to reduce biotin interference.

The modified Assays are comprised of the following components:

Dimension® LOCI® Thyroid Stimulating Hormone Flex® reagent cartridge (TSHL): prepackaged liquid reagents in a plastic eight-well cartridge. Wells 1-2 contain Biotinylated TSH antibody (7.5 µg/mL mouse monoclonal), wells 3-4 contain TSH antibody coated Chemibeads (200 µg/mL mouse monoclonal), and wells 5-6 contain Streptavidin Sensibeads (1400 µg/mL recombinant E. coli). Wells 1-6 contain buffers, stabilizers and preservatives. Wells 7-8 are empty.

Dimension® LOCI® Free Thyroxine Flex® reagent cartridge (FT4L): prepackaged liquid reagents in a plastic eight-well cartridge. Wells 1-2 contain Streptavidin Sensibeads (225 µg/mL recombinant E. coli), wells 3-4 contain T3 Chemibeads (200 µg/mL), and wells 5-6 contain FT4 Biotinylated antibody (50 ng/mL mouse monoclonal). Wells 1-6 contain buffers, stabilizers and preservatives. Wells 7-8 are empty.

Test Principle: Both devices use a homogeneous chemiluminescent immunoassay based on LOCI® technology.
For TSHL, it's a sandwich immunoassay where sample is incubated with biotinylated antibody and Chemibeads to form bead-TSH-biotinylated antibody sandwiches. Sensibeads are added and bind to the biotin to form bead-pair immunocomplexes. Illumination at 680 nm generates singlet oxygen from Sensibeads which diffuses into Chemibeads, triggering a chemiluminescent reaction. The resulting signal is measured at 612 nm and is a direct function of TSH concentration.
For FT4L, it's a sequential immunoassay where sample is incubated with biotinylated antibody. T3 Chemibeads are added and form bead/biotinylated antibody immunocomplexes with the non-saturated fraction of the biotinylated antibody. Sensibeads are then added and bind to the biotin to form bead pair immunocomplexes. Illumination at 680 nm generates singlet oxygen from Sensibeads which diffuses into the Chemibeads, triggering a chemiluminescent reaction. The resulting signal is measured at 612 nm and is an inverse function of FT4 concentration.

The document provided is a 510(k) clearance letter from the FDA for two in-vitro diagnostic (IVD) devices: Dimension® LOCI® Thyroid Stimulating Hormone Flex® reagent cartridge (TSHL) and Dimension® LOCI® Free Thyroxine Flex® reagent cartridge (FT4L). It describes the devices, their intended use, and the performance characteristics tested to demonstrate substantial equivalence to previously cleared predicate devices.

However, it's crucial to understand that this document describes a reagent cartridge, which is a laboratory assay, not an AI/ML-driven device or an imaging device. Therefore, many of the requested criteria (e.g., sample size for training/test sets for AI, data provenance like country of origin for AI, ground truth establishment by experts, adjudication methods, MRMC studies, standalone AI performance) are not applicable to this type of device. The document details the performance of the assay itself in measuring biomarker concentrations, not an AI's ability to interpret images or assist human readers.

I will interpret the request based on the information provided for this specific IVD device, noting where certain requested details are not relevant to the nature of the device.

Acceptance Criteria and Study to Prove Device Meets Criteria (for an IVD Reagent Cartridge)

The device in question, a reagent cartridge for quantitative measurement of TSH and FT4, is a laboratory assay, not an AI/ML or imaging interpretation device. Therefore, the "acceptance criteria" and "study" are focused on analytical performance characteristics (accuracy, precision, linearity, interference, detection limits, etc.) compared to a predicate device, rather than diagnostic accuracy metrics of an AI.

1. Table of Acceptance Criteria and Reported Device Performance

For an IVD reagent cartridge, "acceptance criteria" are typically defined by ranges, limits, or statistical agreementsdemonstrating analytical performance comparable or superior to the predicate device and meeting relevant clinical or analytical standards (e.g., CLSI guidelines). The reported performance demonstrates that the modified devices meet these standards.

2. Sample Sizes and Data Provenance for the Test Set

The concept of a "test set" in the context of an IVD reagent cartridge refers to the set of samples used for various analytical performance studies. These are not typically split into "training" and "test" sets as in AI/ML.

• Method Comparison:
  • TSHL: 145 patient samples (serum)
  • FT4L: 146 patient samples (serum)
• Precision (Repeatability): 5 serum samples (TSHL), 3 serum samples (FT4L)
• Precision (Reproducibility): 5 serum samples (TSHL), 3 serum samples (FT4L)
• Linearity: Low and high human serum pools used to create dilution series (TSHL: 12 levels, FT4L: 10 levels)
• Interference (Biotin and HIL): Samples spiked with interferents, specific TSH/FT4 levels tested.
• Dilution Recovery: 7 samples (TSHL)
• Reference Range Verification: "Apparently healthy samples" (specific N not provided, but typically a statistically significant number for verification per CLSI EP28-A3C).
• Matrix Comparison: Samples of various tube types (Serum, lithium heparin, sodium heparin, K2-EDTA plasma)

Data Provenance: The document does not specify the country of origin of the patient samples. The studies are explicitly described as analytical performance studies rather than clinical outcome studies, and they are retrospective (samples tested in the lab, not followed prospectively).

3. Number of Experts and Qualifications for Ground Truth

This is not applicable as the device is a quantitative IVD assay (reagent cartridge), not an AI/ML device requiring expert interpretation of complex clinical data or images. The "ground truth" for this device is the actual concentration of TSH or FT4 in the sample, typically established either by:

• Reference methods (e.g., mass spectrometry, although not explicitly stated as the ground truth method here).
• The predicate device itself (as used in method comparison studies, where the predicate is the "comparison assay").
• Spiking known concentrations into matrices.

4. Adjudication Method for the Test Set

This is not applicable for a quantitative IVD reagent. Adjudication methods (e.g., 2+1, 3+1) are typically used in scenarios where human experts interpret data (like medical images), and their disagreements need to be resolved to establish a definitive ground truth for AI model evaluation.

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

This is not applicable. An MRMC study is designed to evaluate the diagnostic performance of human readers, often with and without AI assistance, on a set of cases. This device is a reagent cartridge that provides a quantitative measurement, not an AI that assists human interpretation.

6. Standalone Performance (Algorithm Only Without Human-in-the-Loop)

This is not applicable. This device is a reagent cartridge that runs on an automated system, providing a quantitative result. It's inherently "standalone" in providing the measurement, but it's not an "algorithm only" in the sense of an AI interpreting complex data. The performance metrics listed (precision, accuracy relative to predicate, linearity, etc.) are its "standalone" performance.

7. Type of Ground Truth Used

The "ground truth" for this type of quantitative diagnostic test is based on:

• Comparison to a legally marketed predicate device: The current, FDA-cleared versions of the TSHL and FT4L assays (K081074 and K073604) acted as the "gold standard" or comparison method for the method comparison studies.
• Known concentrations: For linearity, recovery, and interference studies, samples were prepared with known concentrations or spiked with known amounts of analytes or interferents.
• Analytically verified samples: Samples used for precision studies have mean values derived from repeated measurements.

8. Sample Size for the Training Set

This is not applicable as the device is a non-AI/ML IVD reagent cartridge. There is no concept of a "training set" for this type of product. The development and optimization of the reagent formulation are internal processes, but they don't involve "training" a model on a dataset in the AI sense.

9. How Ground Truth for the Training Set Was Established

This is not applicable for the same reason as point 8.

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