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The Diazyme 25-hydroxy Vitamin D Assay is designed for the quantification of total 25-hydroxy Vitamin D in human serum and plasma. The assay results are to be used in parallel with other clinical data to assess the Vitamin D status of a patient. For in vitro diagnostic use only.

The 25-hydroxy Vitamin D Assay Calibrator set is intended for use in the calibration of the Diazyme 25-OH Vitamin D Assay Kit only. For in vitro diagnostic use only.

The 25-hydroxy Vitamin D Assay Control kit is intended for use as quality controls for the Diazyme 25-OH Vitamin D Assay kit only. For in vitro diagnostic use only.

The 25-hydroxy (25-OH) Vitamin D assay is based on the principle of x-complementation of the enzyme B-galactosidase and the competition between an enzyme donor-25-OH Vitamin D conjugate, Vitamin D binding protein and the 25-OH Vitamin D content of a serum sample. Samples with higher 25-OH Vitamin D concentrations produce higher ß-galactosidase activities and vice versa. Chlorophenol red-B-D- galactopyranoside (CPRG) is used as the enzyme substrate and the accumulation of the reaction's product (chlorophenol red) is monitored at 560 nm. The 25-OH Vitamin D concentration of a patient sample is proportional to the measured ß-galactosidase activity. The assay consists of a sample extraction step during which Vitamin D is irreversibly dissociated from its serum transporter. Extracted samples are then analyzed on a microplate reader after the sequential addition of three reagents.

25-OH Vitamin D assay calibrator set is intended for use with the Diazyme 25-OH Vitamin D assay kit only. Six calibration levels are needed for each run. Calibrators are treated exactly the same as patient samples.

25-OH Vitamin D assay 2-point control set is intended for use with the Diazyme 25-OH Vitamin D assay kit only. Controls are treated exactly the same as patient samples. The quality controls assist laboratory users in verification steps ensuring that the assay reagents are functioning correctly. Users are instructed to verify the calibration curve with the controls and run controls each time a new lot of reagents are received.

Here's a breakdown of the acceptance criteria and the study details for the Diazyme 25-OH Vitamin D Assay Kit, based on the provided 510(k) summary:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Precision Study:
  • Test Set Size: 40 data points per sample/control level. A total of 9 different samples/controls were tested. This means 40 data points were collected for each of the 7 initial levels and 40 each for the two additional levels (severely deficient and very high).
  • Data Provenance: Not explicitly stated, but implies samples were analyzed in a laboratory setting for internal validation.
• Linearity/Reportable Range:
  • Test Set Size: 11 levels of linearity, each tested in triplicates.
  • Data Provenance: Not explicitly stated, but implies samples were prepared and analyzed in a laboratory setting.
• LoB/LoD/LoQ:
  • Test Set Size: Not explicitly stated how many individual samples were used, but the determination was according to CLSI EP17-A, which specifies protocols for these limits.
  • Data Provenance: Not explicitly stated.
• Analytical Specificity (Interference & Cross Reactivity):
  • Test Set Size: Not explicitly stated how many replicates or individual samples, but tested against specified interferents and cross-reactants at given concentrations.
  • Data Provenance: Not explicitly stated.
• Method Comparison:
  • Test Set Size: 80 human serum samples.
  • Data Provenance: Human serum samples; country of origin not specified.
• Matrix Comparison:
  • Test Set Size: 26 samples for Serum vs Li-Heparin plasma; 55 samples for Serum vs K3-EDTA plasma.
  • Data Provenance: Not explicitly stated (human samples implied).
• Reference Range Study:
  • Test Set Size: 150 apparently healthy individuals.
  • Data Provenance: Prospective collection.
    • 30 samples from Pennsylvania (Northern U.S.) from an FDA Licensed Donor Center.
    • 60 samples from Tennessee (Central U.S.) collected by ProMedDx, LLC per IRB approved protocol.
    • 60 samples from Texas (Southern U.S.) collected by ProMedDx, LLC per IRB approved protocol.
    • All samples collected in October and November 2010.

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

There are no experts mentioned for establishing ground truth as this is a quantitative in vitro diagnostic assay. The "ground truth" or reference values for performance studies (precision, linearity, LoB/LoD/LoQ, analytical specificity) are established by the analytical reference methods or prepared standards used in the laboratory for evaluation, not by human expert consensus or clinical assessment of individual samples for the purpose of algorithm validation.

For the Method Comparison study, the "predicate method" (IDS 25-OH Vitamin D EIA, K021163) serves as the reference for comparison, not an expert panel.

4. Adjudication Method for the Test Set

Not applicable. This is a quantitative diagnostic assay; there is no expert adjudication process described for the assay's performance studies. Results are compared to predefined analytical criteria or a predicate device.

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

No, an MRMC comparative effectiveness study was not done. This is an in vitro diagnostic (IVD) assay that quantitatively measures a biomarker, not an imaging device or AI algorithm requiring human-in-the-loop assessment and comparative effectiveness with or without AI assistance.

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

Yes, the studies reported are essentially standalone performance evaluations of the Diazyme 25-OH Vitamin D Assay Kit. The device provides a quantitative measurement and its performance is assessed intrinsically (e.g., precision, linearity) and compared to a predicate device, without direct human interpretation or involvement in arriving at the measurement result itself. The use of results in parallel with other clinical data for patient assessment is a clinical interpretation step, but the device's performance metrics are standalone.

7. The Type of Ground Truth Used

The "ground truth" in this context refers to the verifiable reference values against which the device's performance is measured:

• Precision, Linearity, LoB/LoD/LoQ, Analytical Specificity: Established by laboratory analytical standards, reference materials, defined diluent concentrations, and established CLSI protocols.
• Method Comparison: The predicate device (IDS 25-OH Vitamin D EIA, K021163) served as the reference method for comparison.
• Reference Range Study: The concentrations of 25-OH Vitamin D in the collected samples from apparently healthy individuals were measured by the Diazyme assay itself to establish the device's own reference interval. This is based on measured values from a defined population, not an external "ground truth" as such.

8. The Sample Size for the Training Set

Not applicable. This is not an AI/ML device that requires a training set in the conventional sense. The device is a chemical assay kit.

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

Not applicable, as no training set (for AI/ML) is mentioned or implied for this device.

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