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Radioimmunoassay for the quantitative measurement of free testosterone in human serum. This assay is intended for in vitro diagnostic use.

Free testosterone test is used in the diagnosis and treatment of disorders involving the male sex hormones (androgens), including primary and secondary hypogonadism, delayed or precocious puberty, impotence in males and, in female's hirsutism (excessive hair) and virilization (masculinization) due to tumors, polycystic ovaries, and adrenogenital syndromes.

The radioimmunoassay of free testosterone is a competitive assay. The procedure follows the basic principle of radioimmunoassay where there is competition between a radioactive and a non-radioactive antigen for a mixed number of antibody binding sites. The amount of [125]]-labeled testosterone analog bound to the antibody is inversely proportional to the concentration of unlabeled free testosterone present. The separation of the free and bound antigen is achieved by decanting or aspirating the antibody-coated tubes. A standard curve is constructed and unknown free testosterone values are obtained from the curve by interpolation.

Kit Content:
Free Testosterone Antibody-Coated Tubes: 2 x 50 tubes (ready-to-use)
125|-labeled Testosterone Analog Tracer (YELLOW): one 22 mL vial (ready-to-use)
Calibrators: one 1.0 mL vial labeled 0, and seven 0.5 mL vials labeled 1-7 (ready-to-use)
Controls: two 0.5 mL vials labeled 1, 2 (ready-to-use)

The provided text describes the Immunotech ACTIV\u00AE Free Testosterone RIA device, a radioimmunoassay for the quantitative measurement of free testosterone in human serum. This is an in vitro diagnostic device and the information provided is a 510(k) summary, which is typically for demonstrating substantial equivalence to a legally marketed predicate device.

Here's an analysis of the acceptance criteria and study information:

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present "acceptance criteria" for overall device performance in the form of pass/fail thresholds for clinical utility. Instead, it provides a summary of the analytical performance characteristics and reference ranges, which are the results of validation studies conducted to support the device's claims and demonstrate its performance.

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

The document describes specific sample sizes for different analyses:

• Method Comparison: N = 278 samples were used to compare the proposed device with the predicate. The dataProvenance is implicitly retrospective as it compares results from two versions of a device, likely using banked samples or samples run consecutively.
• Expected Values/Reference Ranges:
  • Men: N = 120 (30 per age group: 20-29, 30-39, 40-49, 50+).
  • Women: N = 120 (32 follicular, 32 luteal, 21 preovulatory peak, 13 postmenopausal, 19 contraceptives \u2013 totaling 117 individual samples given in the subcategories, implying some overlap or missing a few for the total of 120 "Random Women").
  • Boys: N = 114 (18 infant, 48 child, 30 adolescent in one grouping; 36 6m-9y, 20 10-11y, 20 12-13y in another grouping - these age ranges seem to be different categorizations of the same underlying data or separate cohorts).
  • Girls: N = 119 (34 infant, 55 child, 30 adolescent in one grouping; 69 6m-9y, 20 10-12y, 20 13-16y in another grouping - similar to boys, likely different categorizations or cohorts).

The data provenance is not explicitly stated (e.g., country of origin). Given the manufacturer is based in the Czech Republic, the samples could be from Europe, but this is not confirmed. The nature of these studies (establishing reference ranges) suggests they are prospective or retrospective collections specific for this type of validation.

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

This section is not applicable to this type of device and study. The device, Immunotech ACTIV\u00AE Free Testosterone RIA, is an in vitro diagnostic (IVD) test that measures a quantitative biomarker concentration (free testosterone in serum). The "ground truth" for such a device is established through:

• Reference measurement procedures (RMPs) or reference methods, which are highly accurate and precise analytical techniques.
• Certified reference materials (CRMs) with known concentrations.
• Comparisons to a legally marketed predicate device (as is the case here).

Experts, clinical consensus, or pathology are typical for image-based diagnostic AI, not for quantitative chemical assays.

4. Adjudication Method for the Test Set

This section is not applicable for this type of in vitro diagnostic device. Adjudication methods (like 2+1, 3+1) are typically used in clinical studies or studies involving human interpretation (e.g., radiology for AI interpretation) to establish a consensus ground truth. For an IVD, the measurement itself using a validated method is the "truth," or the comparison is made against a validated predicate device.

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

No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done. MRMC studies are specific to evaluating devices (often AI-powered) that assist human readers (e.g., radiologists, pathologists) in making diagnoses. This device is a quantitative immunoassay, not a reader-assisted diagnostic tool.

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

Yes, the performance characteristics provided (sensitivity, specificity, precision, measurement range, interference, linearity, cross-reactivity, method comparison) represent the standalone performance of the assay itself, as an in vitro diagnostic test. There is no human intervention in the result generation beyond operating the instrument and following the assay procedure.

7. The Type of Ground Truth Used

The ground truth for evaluating the analytical performance of the device is established using:

• Internal standards for calibrator values.
• Reference materials/samples with known concentrations for sensitivity, linearity, and interference studies (though not explicitly detailed, this is standard practice for CLSI guidelines).
• Comparison to a legally marketed predicate device (ACTIV\u00AE Free Testosterone RIA, K952281) for method comparison, which serves as a high-quality comparator given its prior FDA clearance.
• Clinically characterized samples (e.g., from different age groups, sexes, and physiological states) to establish expected values/reference ranges.

The document implicitly uses these standard analytical validation approaches rather than, for instance, pathology or outcomes data (which would be for clinical utility, not analytical performance).

8. The Sample Size for the Training Set

This document only details validation and verification activities, not the development or "training" of the assay. For a traditional immunoassay like this RIA, there isn't a "training set" in the context of machine learning or AI. The assay's "design" is based on biochemical principles (antibody-antigen binding) rather than statistical learning from a dataset. The formulation of reagents, selection of antibody, and optimization of the protocol would involve internal R&D, but not a formally defined "training set" with ground truth in the AI sense.

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

As stated above, this is not applicable for a traditional immunoassay. The concept of a "training set" and "ground truth" establishment in the context of AI does not directly translate to the development process of this type of diagnostic kit.

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