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The AquaLite® Intact PTH Bioluminescent Immunoassay (BLA) Kit (or the AquaLite® Intact PTH assay) is intended to be used in clinical laboratories for the quantitative determination of human intact parathyroid hormone in serum mongunested, Intact PTH measurements are used in the diagnosis of disorders of calcium metabolism and the parathyroid gland. The AquaLite® Intact PTH assay is for in vitro diagnostic use.

The AquaLite® Intact PTH Bioluminescent Immunoassay Kit uses a goat polyclonal anti-PTH antibody that is pre-coated onto polystyrene tubes (solid phase). Serum samples, appropriate calibrators, and controls, are pipetted (100uL) into the pre-coated tubes. A second goat polyclonal anti-PTH antibody covalently linked to AquaLite® (150µL) is then added to the tubes. Intact PTH in the sample simultaneously combines with anti-PTH antibody on the solid phase and conjugate antibody to form an immune complex or "sandwich" bound to the solid phase. Complex formation is complete after a 120-minute incubation period at room temperature (18° to 25°C) on a standard orbital shaker. The tubes are then washed to remove unbound conjugate.

The washed tubes are placed in a luminometer that is capable of reading a triggered. flash-type reaction in 12 x 75 mm tubes. Injection of the calcium trigger buffer causes AquaLite® to oxide its self-contained luciferin molecule, producing a flash of light which is measured by the luminometer. The intensity of the light emitted from antibody bound to the tubes is directly proportional to the concentration of intact PTH in the sample. To calculate results, the luminometer uses a cubic spline curve fit applied to a logit-log transformation of the light intensity (in relative light units, RLU) of the intact PTH calibrators versus intact PTH concentration (in pg/mL).

Here's a breakdown of the acceptance criteria and study information for the SeaLite Sciences, Inc. AquaLite® Intact PTH device, based on the provided text:

Acceptance Criteria and Reported Device Performance

• 1-34 fragment (400 pg/mL): 50% inhibition
• 39-84 fragment (100,000 pg/mL): 0% inhibition
• 53-84 fragment (100,000 pg/mL): 0% inhibition
• 39-68 fragment (100,000 pg/mL): 0% inhibition
• 44-68 fragment (100,000 pg/mL): 0% inhibition |
  | High Dose Hook Effect | No hook effect at high concentrations of intact PTH | No high dose hook effect prior to 100,000 pg/mL |
  | Precision | Intra-assay: Low coefficient of variation (CV) within a single assay |
• PTH Level 26.10 pg/mL: 6.95% CV
• PTH Level 173.71 pg/mL: 5.45% CV |
  | | Inter-assay: Low coefficient of variation (CV) across multiple assays |
• PTH Level 51.7 pg/mL: 8.9% CV
• PTH Level 332.3 pg/mL: 8.3% CV |
  | Method Comparison | Good correlation with a commercially available chemiluminometric kit for PTH |
• Slope: 0.964
• Y-intercept: 10.017
• Correlation coefficient: 0.95 |
  | Linearity and Nonparallelism | Consistent recovery across dilutions of human serum samples |
• Sample A: Recovery 103-106%
• Sample B: Recovery 99-108%
• Sample C: Recovery 100-105% |
  | Recovery | Consistent recovery when mixing PTH serum samples in various ratios |
• Sample A (2A:1B, 1A:1B, 1A:2B): Recovery 89-93%
• Sample C (2C:1D, 1C:1D, 1C:2D): Recovery 90-92% |
  | Overall Performance | Similar and substantially equivalent to other commercially available assays for intact PTH | Data demonstrate similarity and substantial equivalence |

Study Details

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

   • Specificity: Not explicitly stated, but involves spiking a sample (17 pg/mL) with PTH fragments.
   • Precision:
     • Intra-assay: 20 replicates for each of two commercial control concentrations.
     • Inter-assay: 20 assays (each with duplicate measurements, so a total of 40 measurements) for each of two commercial control concentrations.
   • Method Comparison: 57 patient samples.
   • Linearity and Nonparallelism: 3 human serum samples, each diluted and assayed in duplicate.
   • Recovery: Not explicitly stated, but involved mixing multiple PTH serum samples in various ratios and assaying in duplicate.
   • Data Provenance: Studies were conducted at SeaLite Sciences, Inc. The samples for Method Comparison are referred to as "patient samples," but no specific country of origin or whether they were retrospective or prospective is mentioned. Commercial controls and human serum samples were also used.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience):

   • Not applicable. This device is an in vitro diagnostic (IVD) assay that measures a biomarker (Intact PTH). The "ground truth" for method comparison is another commercially available chemiluminometric kit, not expert interpretation. For other performance characteristics, the "ground truth" is based on expected values for controls, dilutions, or spiked samples.

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

   • Not applicable. This is an IVD assay, not a device that relies on human interpretation requiring adjudication.

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-assisted diagnostic tool that involves human readers.

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

   • Yes, the entire study focuses on the standalone performance of the AquaLite® Intact PTH assay (algorithm/device only). The method comparison is against another standalone commercial assay.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

   • The "ground truth" varies depending on the specific performance characteristic:
     • Sensitivity: Defined by statistical calculation from the zero calibrator.
     • Specificity: Based on expected behavior with known PTH fragments.
     • Precision: Based on repeated measurements of known control samples.
     • Method Comparison: Comparison against a "commercially available chemiluminometric kit for PTH." This kit serves as the reference standard.
     • Linearity and Recovery: Based on calculated expected values after dilution or mixing of samples.

7. The sample size for the training set:

   • Not applicable. This document describes the performance characteristics and validation of a laboratory assay, not a machine learning model that requires a "training set" in the typical sense. The assay is based on chemical reactions and luminosity measurements, not an algorithm that learns from data.

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

   • Not applicable, as there is no training set for this type of IVD device.

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