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ACE T Uptake Reagent is used in the diagnosis and treatment of thyroid disorders. It is intended for the quantitative determination of unsaturated binding sites on the thyroid-binding proteins in serum using the ACE clinical chemistry analyzer.

The ACE T Uptake Regent contains two reagents, and Antibody/Substrate reagent and an Enzyme The assay uses a mixture of enzyme glucose-6-phosphate dehydrogenase Conjugate reagent. conjugated thyroxine (G6PD-T4) and a known amount of exogeneous T4 which is allowed to bind to the thyroxine-binding proteins in the sample. A sample with increased levels of unsaturated thyroxine-binding sites, the exogeneous T4 will bind leaving G6PD-T4 conjugate free. On addition of an anti-thyroxine antibody, the G6PD-T4 conjugate is bound by the antibody and the enzyme activity is inhibited. Conversely, a sample with decreased levels of unsaturated thyroxine-binding sites will leave most exogeneous T4 unbound. Upon addition of anti-T4 antibody, the unbound exogeneous T4 will inhibit the anti-T4 binding to G6PD-T4 conjugate and produce a high G6PD enzyme activity. This phenomenon creates a relationship between unsaturated thyroxine-binding sites concentration (T Uptake) and the enzyme activity. The enzyme G6PD activity is determined bichromatically on the ACE® at 340/505 nm by measuring its ability to convert NAD* to NADH.

Acceptance Criteria and Device Performance Study for ACE® T Uptake Reagent (K981375)

This document describes the acceptance criteria and a summary of the performance study for the ACE® T Uptake Reagent, based on the provided 510(k) premarket notification.

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria for the ACE® T Uptake Reagent are implicitly defined by its substantial equivalence to the predicate device (Diagnostic Reagents, Inc. T Uptake Enzyme Immunoassay, K951586). The study aimed to demonstrate that the new device's performance characteristics are comparable to, or better than, the predicate device.

Note: The document explicitly states that "Based on these data, the Schiapparelli Biosystems ACE® T Uptake Reagent is substantially equivalent to the predicate device." This implies that meeting or closely matching the predicate's performance metrics served as the acceptance criteria.

2. Sample Size and Data Provenance for the Test Set

• Sample Size (for correlation study): N = 50
• Data Provenance: The document does not explicitly state the country of origin or whether the data was retrospective or prospective. However, given that this is a 510(k) submission for a diagnostic reagent, it is highly probable that the data was generated prospectively during a validation study conducted in a clinical laboratory setting, likely within the United States.

3. Number and Qualifications of Experts for Ground Truth

• Number of Experts: Not applicable. This type of device (reagent for quantitative determination) does not typically involve expert interpretation of results for establishing ground truth in the same way an imaging device might. The "ground truth" for the test set is established through comparison with a recognized reference method or predicate device.
• Qualifications of Experts: Not applicable for this specific type of device and study design.

4. Adjudication Method for the Test Set

• Adjudication Method: Not applicable. The "ground truth" is established by the results of the comparative methods (predicate device and Hitachi 717 Assay for T Uptake), not through expert adjudication. Discrepancies would be handled through technical investigation of the assay performance, not by an adjudication panel.

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

• MRMC Study: No. A multi-reader multi-case (MRMC) comparative effectiveness study is not relevant for this type of in vitro diagnostic (IVD) reagent. MRMC studies are typically performed for imaging or interpretation-based diagnostic devices where human readers are involved in the diagnostic process.

6. Standalone (Algorithm Only) Performance

• Standalone Performance Study: Yes, in effect. The performance data presented (Assay Range, Precision, Correlation) directly reflects the standalone performance of the ACE® T Uptake Reagent as an algorithm/reagent system. There is no human-in-the-loop component in the fundamental operation of this quantitative assay. The device itself (ACE® T Uptake Reagent) is the "algorithm" and its performance is evaluated directly.

7. Type of Ground Truth Used

• Type of Ground Truth: The ground truth for the performance assessment was established through comparison with a legally marketed predicate device (Diagnostic Reagents, Inc. T Uptake Enzyme Immunoassay) and another commercial assay (Hitachi 717 Assay for T Uptake). Specifically, the correlation study used the results from these established methods as the reference for assessing the accuracy of the proposed device.

8. Sample Size for the Training Set

• Sample Size for Training Set: The document does not provide specific information about a dedicated "training set" sample size. For IVD reagents like this, the development process typically involves internal validation and optimization using various samples, but these are not usually formally termed "training sets" in the same way as machine learning algorithms. The performance assessment data N=50 likely represents a portion of the validation data.

9. How Ground Truth for the Training Set Was Established

• How Ground Truth for Training Set Was Established: As mentioned above, the concept of a "training set" and its explicit ground truth establishment is not typically documented in this manner for traditional IVD reagent submissions. The device's methodology (enzyme immunoassay) is based on established biochemical principles. Ground truth for optimizing and calibrating such a reagent would be derived from:
  • Known concentration standards: Using commercially prepared or internally validated standards with defined T Uptake values.
  • Reference materials: Using biological samples with assigned values from reference laboratories or methods.
  • Comparison to existing, validated methods: Initial development and optimization would likely involve running samples in parallel with accepted methods to ensure the new reagent provides accurate and reliable results.

Overall, the study demonstrates substantial equivalence to the predicate device by showing comparable assay range, precision, and a strong correlation with both the predicate and another commercial T Uptake assay.

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The Measurement of the Total Amount of Binding Sites Available for the Thyroid Hormones in Human Serum or Plasma by a Microplate Enzyme Immunossay. Measurements obtained from this device are used in the diagnosis and treatment of thyroid diseases.

The Monobind microplate EIA utilizes limited amount of anti-thyroxine antibody coated on the surface of plastic wells of a microtiter plate. Specimens, calibrators or controls are then added followed by the enzyme-T4 conjugate and thyroxine. The amount of enzyme only gets to the specimen increases. After the completion of the incubation period, the enzyme-T4 conjugate on the well is quantitated by reaction with suitable substrate. The activity of the enzyme is inversely proportional to the amount of unsaturated thyroid hormone binding sites in the specimen. The employment of several serum references of known unsaturated thyroid hormone binding capacity permits construction of a graph of absorbance and concentration. From comparison to the dose response curve, an unknown specimen's absorbance can be correlated with thyroid hormone binding capacity.

Here's an analysis of the provided text to extract information about the acceptance criteria and study for the Monobind T-Uptake Microplate EIA device:

1. Table of Acceptance Criteria and Reported Device Performance

The submission does not explicitly state formal "acceptance criteria" in a quantitative manner (e.g., "sensitivity must be >X%, specificity >Y%"). Instead, it focuses on demonstrating "substantial equivalency" to a predicate device. The primary performance metric reported to support this equivalency is related to method agreement.

• Sample Size: 120 specimens
• Specimen Types: Hypothyroid, pregnant, euthyroid, and hyperthyroid populations.
• Mean Values:
  • Reference method (radioassay): 29.0
  • This method (microplate EIA): 29.3
• Linear Regression Equation: y = 1.56 + 0.96x
• Correlation Coefficient: 0.972
  Conclusion: These results "indicate good method agreement," suggesting substantial equivalency. |

2. Sample Size Used for the Test Set and Data Provenance

• Sample Size for Test Set: 120 specimens.
• Data Provenance: Not explicitly stated (e.g., country of origin). The data is described as "clinical comparison" using specimens from different patient populations, suggesting it is retrospective or prospective clinical data collected for the purpose of this comparison. It is not stated as simulated data.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

This information is not provided in the document. The ground truth for the test set is established by the predicate device (Monobind T3 Uptake radioassay), not by human experts adjudicating results.

4. Adjudication Method for the Test Set

This information is not applicable as the ground truth for the test set was established by the predicate device's measurements, not by human expert adjudication.

5. 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

This is not applicable. The device is an immunoassay (laboratory test), not an AI-assisted diagnostic imaging or interpretation tool for human readers. Therefore, an MRMC study comparing human reader performance with and without AI assistance would not be relevant.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

Yes, the study presented is a standalone performance study for the Monobind T-Uptake Microplate EIA. The device itself performs the measurement, and its results are compared directly to those of the predicate device. There is no human-in-the-loop aspect described for the performance evaluation of the device output itself, though human involvement is required for specimen collection, assay performance, and result interpretation in a clinical setting.

7. The Type of Ground Truth Used

The ground truth used for performance evaluation (specifically, establishing substantial equivalence) was the measurements obtained from a legally marketed predicate device (Monobind T3 Uptake radioassay). This serves as the "reference method" against which the new device's performance is compared.

8. The Sample Size for the Training Set

The document does not explicitly mention a separate "training set". For immunoassay development, reference materials, calibrators, and perhaps internal development studies would be used during the R&D phase to optimize the assay. However, the provided text describes the validation/clinical comparison study for regulatory submission, which is analogous to a test set in the context of demonstrating performance for regulatory approval.

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

As no specific "training set" is disclosed in the provided document, the method for establishing its ground truth is not available. However, typically for an immunoassay, the "ground truth" for developing and optimizing calibrators and controls (which might be considered analogous to training data in some contexts) would be based on established analytical methods, certified reference materials, or clinical samples with known characteristics, often determined by reference laboratories or established predicate methods.

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For the assessment of unsaturated thyroid binding proteins in serum or plasma using the Chiron Diagnostics ACS:180® Automated Chemiluminescence Systems.

The thyroid hormones triiodothyronine (T3) and thyroxine (T4) are bound primarily to thyroxine-binding globulin (TBG) and to a lesser extent thyroxine-binding prealbumin (TBPA) and albumin. The ACS:180 T Uptake assay measures the number of unoccupied binding sites on these proteins and is an indirect indicator of thyroid status.

T Uptake (TU) and total T4 are used to estimate the amount of circulating free T4. The estimate, or the Free Thyroxine Index (FTI), is a normalized measurement that remains relatively constant in healthy individuals and compensates for abnormal levels of binding proteins, which can occur in many different physical conditions.

Drugs or physical conditions that alter the patient's TBG levels or drugs that compete with endogenous T4 and T3 for protein-binding sites alter T Uptake results.

When serum contains high levels of T3 or T4, as in hyperthyroidism, fewer unoccupied binding sites are available. Conversely, in hypothyroidism, more binding sites are available.

The Chiron Diagnostics ACS:180 TUp assay is a double antibody competitive immunoassay using, chemiluminescent technology. The sample is incubated with Lite Reagent, which is composed of acridinium ester-labeled T3-BGG (bovine gamma globulin) and unlabeled T3. The unlabeled T3 in the Lite Reagent fills available thyroid-binding sites in the sample. The acridinium ester-labeled T3-BGG does not bind to the binding proteins in the sample.

The acridinium ester-labeled T3-BGG and unlabeled T3 compete for monoclonal mouse anti-T3 antibody in the Solid Phase. The monoclonal mouse anti-T3 antibody is bound to goat anti-mouse antibody, which is covalently coupled to paramagnetic particles in the Solid Phase. A greater amount of unlabeled T3 binding to the binding proteins in the sample results in more T3-BGG-acridinium ester binding to the monoclonal antibody, an indication of a higher amount of unsaturated binding proteins.

This document describes a medical device called the "Chiron Diagnostics ACS:180 TUp," a thyroid hormone uptake test system.

Here's an analysis of the provided information according to your request:

Acceptance Criteria and Device Performance

The document does not explicitly define "acceptance criteria" for the device's performance in terms of accuracy or precision against a specific threshold. Instead, it presents performance characteristics such as:

• Reference Range: Established for euthyroid individuals.
• Specificity: Cross-reactivity with various compounds.
• Method Comparison: Correlation with an alternate chemiluminescent method.
• Precision: Within-laboratory precision (Total CV).

Given the absence of explicit acceptance criteria, the "Reported Device Performance" below summarizes the results provided for each characteristic.

Table of Acceptance Criteria and Reported Device Performance

• TU Ratio: 0.75 – 1.23
• % TU: 22.5 – 37.0
• FTI: 1.4 – 3.1 |
  | Specificity | Implied: Demonstrate low cross-reactivity with structurally similar compounds and non-target analytes. | Cross-reactivity:
• L-thyroxine: 0.95 or similar) with an established reference/predicate method. | Correlation with alternate chemiluminescent method:
• T Uptake Ratio: r = 0.95
• FTI: r = 0.97 (Equation: ACS:180 TUp FTI = 1.07 * (alternate method) + 0.04) |
  | Precision (Total % CV) | Implied: Demonstrate acceptable within-laboratory precision for different sample concentrations. (No specific numerical target given for %CV, but typically

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Immunoassay for the in vitro quantitative determination of thyroxine-binding capacity in human serum and plasma.

The Elecsys® test principle is based on competition principle. Total duration of assay: 18 minutes (37° C).
• 1st incubation (9 minutes): Sample (15 $\mu$ L), exogenous T4, and biotinylated T4-polyhapten (75 $\mu$ L).
•2nd incubation (9 minutes): After addition of a specific anti-T4 antibody labeled with a ruthenium complex (75 $\mu$ L), the polyhapten and the antibody derivative react to form a complex, the concentration of which is inversely proportional to the concentration of the excess, exogenous T4. This immunological complex is bound to the added streptavidin-coated microparticles (35 $\mu$ L) via the interaction of biotin and streptavidin.
·The reaction mixture is aspirated into the measuring cell where the microparticles are magnetically captured onto the surface of the electrode. Unbound substances are then removed with ProCell. Application of a voltage to the electrode then induces chemiluminescent emission which is measured by a photomultiplier (0.4 second read frame).
·Results are determined via a calibration curve which is instrumentspecifically generated by 2-point calibration and a master curve provided via the reagent bar code.

The provided text describes the Elecsys® T-Uptake Assay and its comparison to a predicate device, the Enzymun-Test® TBK (T4 Uptake). The studies performed are primarily focused on demonstrating substantial equivalence to the predicate device, rather than establishing acceptance criteria for novel performance.

Here's an analysis of the requested information based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

The document doesn't explicitly state "acceptance criteria" in the traditional sense of pre-defined thresholds for performance success. Instead, it presents a comparison to a predicate device, aiming to show "substantial equivalence." The performance characteristics shown are relative to the predicate and aim to demonstrate comparable or improved performance.

Implicit "Acceptance Criteria" (based on predicate device comparison) and Reported Performance:

2. Sample Size Used for the Test Set and Data Provenance

• Precision:
  • Elecsys® T-Uptake: N=60 for each of the three control levels.
  • Enzymun-Test® TBK (Predicate): N=118 (Low), N=120 (Mid), N=119 (High).
• Method Comparison:
  • Elecsys® T-Uptake vs. Enzymun-Test® TBK: N=319.
• Data Provenance: The document does not specify the country of origin of the data or whether it was retrospective or prospective.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications

N/A. This is a quantitative diagnostic assay for Thyroxine-Binding Capacity. The "ground truth" for such assays is typically established by the reference method or comparison to an established, validated predicate device (as done here). There are no experts establishing ground truth in the sense of image interpretation or clinical diagnosis.

4. Adjudication Method for the Test Set

N/A. As this is not an expert-driven diagnostic interpretation, no adjudication method like 2+1 or 3+1 is applicable.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done

No. This is an in vitro diagnostic device, not an imaging device that would typically involve human readers interpreting cases. Therefore, an MRMC study is not applicable.

6. If a Standalone Study Was Done

Yes, the performance characteristics of the Elecsys® T-Uptake Assay (e.g., precision, lower detection limit, linearity, interfering substances, specificity) were evaluated as a standalone product. However, the primary context for evaluating its performance is always in comparison to the predicate device to establish substantial equivalence.

7. The Type of Ground Truth Used

The ground truth for evaluating the Elecsys® T-Uptake Assay's performance is:

• Analytical Performance: Established through laboratory testing using known controls, standards, and samples for precision, linearity, detection limits, and interference.
• Comparative Performance: Established by comparing its results to a legally marketed predicate device (Enzymun-Test® TBK), which serves as the "reference standard" for demonstrating substantial equivalence.

8. The Sample Size for the Training Set

The document does not explicitly mention a "training set" in the context of machine learning, as this is a chemical assay. The assay's calibration uses a 2-point calibration and a master curve provided via a reagent bar code. The development of the assay itself would have involved extensive R&D and optimization, but the specific sample sizes for such development or "training" (in a non-ML sense) are not provided.

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

N/A. As this is an in vitro diagnostic assay based on a competition principle and electrochemiluminescence, there isn't a "training set" in the machine learning sense. The assay's accuracy and performance are established through rigorous analytical validation against known concentration standards and comparison to established methods, rather than learning from a labeled dataset.

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