ADVIA Centaur Intact Parathyroid Hormone (PTH) Assay

{0} 1 # 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE A. 510(k) Number: k163658 B. Purpose for Submission: New device C. Measurand: Intact Parathyroid Hormone (PTH) D. Type of Test: Quantitative Chemiluminescent Immunoassay E. Applicant: Siemens Healthcare Diagnostics Inc. F. Proprietary and Established Names: ADVIA Centaur Intact Parathyroid Hormone (PTH) Assay G. Regulatory Information: | Product Code | Classification | Regulation Section | Panel | | --- | --- | --- | --- | | CEW | II | 21 CFR 862.1545, Parathyroid hormone test system | Clinical Chemistry (75) | H. Intended Use: 1. Intended use(s): Please refer to the Indications for use below. {1} 2. **Indication(s) for use:** The ADVIA Centaur Intact Parathyroid Hormone (PTH) reagent is for *in vitro* diagnostic use in the quantitative determination of intact parathyroid hormone (PTH) in human serum and plasma using the ADVIA Centaur XP system. This assay is intended to be used to aid in the differential diagnosis of hyperparathyroidism, hypoparathyroidism, or disorders of calcium metabolism. This assay can be used intra-operatively. 3. **Special conditions for use statement(s):** - For *in vitro* diagnostic use only. - For prescription use only. 4. **Special instrument requirements:** - Siemens ADVIA Centaur XP systems. **I. Device Description:** The device consists of the components described below. 1. **ADVIA Centaur PTH Primary Reagent ReadyPack (included in assay kit)** - **ADVIA Centaur PTH Lite Reagent (10.0 mL/pack):** Acridinium ester-labeled mouse monoclonal anti-human PTH antibody (~0.6 mg/L) in buffered saline with mouse gamma globulin, bovine serum albumin, and preservatives. - **ADVIA Centaur PTH Solid Phase Reagent (20.0 mL/pack):** Biotinylated mouse monoclonal anti-human PTH antibody bound to streptavidin-coated paramagnetic particles (~0.4 g/L) in buffered saline with bovine gamma globulin, bovine serum albumin, and preservatives. 2. **ADVIA Centaur PTH Calibrator (included in assay kit)** - **ADVIA Centaur PTH Low and High Calibrators (1.0 mL/vial):** Lyophilized low or high levels of intact PTH synthetic peptide in buffered saline with human EDTA plasma (10%), surfactants, and preservatives. **J. Substantial Equivalence Information:** 1. **Predicate device name(s):** ADVIA Centaur Intact Parathyroid Hormone (iPTH) Assay {2} 2. Predicate 510(k) number(s): k133601 3. Comparison with predicate: | Similarities and Differences | | | | --- | --- | --- | | Item | Candidate Device: ADVIA Centaur Intact Parathyroid Hormone (PTH) Assay (k163658) | Predicate Device: ADVIA Centaur Intact Parathyroid Hormone (iPTH) Assay (k133601) | | Intended Use | For in vitro diagnostic use in the quantitative determination of intact parathyroid hormone (PTH) in human serum and plasma using the ADVIA Centaur XP system. | Same | | Indications for Use | This assay is intended to be used to aid in the differential diagnosis of hyperparathyroidism, hypoparathyroidism, or disorders of calcium metabolism. This assay can be used intra-operatively. | This assay is intended to be used to aid in the differential diagnosis of hyperparathyroidism and hypoparathyroidism. | | Analyte | Intact parathyroid hormone | Same | | Test Principle | Quantitative chemiluminescent immunoassay | Same | | Capture Antibody | Biotinylated mouse monoclonal anti-human PTH antibody with streptavidin-coated paramagnetic particles pre-formed in Solid Phase Reagent | Biotinylated goat polyclonal anti-human PTH antibody with streptavidin-coated paramagnetic particles pre-formed in Solid Phase Reagent | | Detection Antibody | Mouse monoclonal antibody conjugated to Acridium Ester in the Lite Reagent | Goat polyclonal antibody conjugated to Acridium Ester in the Lite Reagent | | Sample Type | Human serum and plasma | Same | | Assay Range | 6.3 – 2000 pg/mL | 6.3 – 1900 pg/mL | | Calibrators | 2 levels of Siemens PTH Calibrators | 2 levels of Siemens iPTH Calibrators | | Calibration procedure | 2 Point | Same | | Expected Values | 18.4 – 80.1 pg/mL (plasma)18.5 – 88.0 pg/mL (serum) | 13.8 – 85.0 pg/mL (plasma)12.4 – 76.8 pg/mL (serum) | {3} K. Standard/Guidance Document Referenced (if applicable): - CLSI EP05-A3: Evaluation of Precision of Quantitative Measurement Procedures; Approved Guideline – Third Edition - CLSI EP06-A: Evaluation of the Linearity of Quantitative Measurement Procedures: A Statistical Approach; Approved Guideline - CLSI EP07-A2: Interference Testing in Clinical Chemistry; Approved Guideline – Second Edition - CLSI EP09-A3: Measurement Procedure Comparison and Bias Estimation Using Patient Samples; Approved Guideline – Third Edition - CLSI EP12-A2: User Protocol for Evaluation of Qualitative Test Performance - CLSI EP17-A2: Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures; Approved Guideline – Second Edition - CLSI EP28-A3c: Defining, Establishing and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline – Third Edition - ANSI/AAMI/ISO 14971:2007/(R)2010: Medical devices – Applications of Risk Management to Medical Devices L. Test Principle: The ADVIA Centaur Intact Parathyroid (PTH) assay is a two-site sandwich immunoassay using direct chemiluminometric technology, and two monoclonal antibodies. The first antibody in the Lite Reagent is a monoclonal mouse anti-human PTH (N-terminal) antibody labeled with acridinium ester. The second antibody is a biotinylated monoclonal mouse anti-human PTH (C-terminal) antibody that is preformed to streptavidin-coated paramagnetic latex particles in the Solid Phase reagent. A direct relationship exists between the amount of PTH present in the patient sample and the amount of relative light units (RLUs) detected by the system. Results are calculated from a master curve adjusted by using high and low calibrators. M. Performance Characteristics (if/when applicable): 1. Analytical performance: a. Precision/Reproducibility: A precision study was performed in accordance with CLSI EP05-A3. Nine (9) samples (6 human K2-EDTA plasma pools and 3 controls) with concentrations spanning the measuring range of the device were tested in duplicate using 2 runs per day over 20 days for a total of 80 replicates per sample. The within-run and total precision results shown in the table below: {4} | | | Within-Run Precision | | Total Precision | | | --- | --- | --- | --- | --- | --- | | | Mean Conc. (pg/mL) | SD | %CV | SD | %CV | | Plasma 1 | 16.9 | 0.9 | 5.16 | 1.1 | 6.78 | | Plasma 2 | 50.3 | 1.4 | 2.78 | 2.3 | 4.57 | | Plasma 3 | 146.4 | 1.9 | 1.30 | 2.9 | 1.95 | | Plasma 4 | 409.2 | 6.8 | 1.67 | 16.9 | 4.13 | | Plasma 5 | 596.3 | 7.3 | 1.23 | 9.7 | 1.62 | | Plasma 6 | 1080.4 | 11.8 | 1.09 | 25.1 | 2.32 | | Control 1 | 41.6 | 0.4 | 0.91 | 1.4 | 3.36 | | Control 2 | 235.9 | 1.9 | 0.81 | 4.4 | 1.85 | | Control 3 | 874.0 | 8.0 | 0.92 | 18.4 | 2.11 | # b. Linearity/assay reportable range: A linearity study was performed in accordance with CLSI EP06-A2. Eleven (11) evenly distributed dilutions were created by mixing a high human EDTA plasma pool and a low human EDTA plasma pool. The samples spanned a PTH range of $2.7\mathrm{pg / mL}$ to $2262.1~\mathrm{pg / mL}$ . The sample set of 11 dilutions was run in triplicate using 3 different reagent lots. The results of a representative reagent lot are summarized below: | Sample | Expected concentration (pg/mL) | Observed Concentration (pg/mL) | Deviation from Linear fit | | --- | --- | --- | --- | | 1 | 2.7 | 2.7 | 3% | | 2 | 3.8 | 3.5 | -4% | | 3 | 7.1 | 6.6 | -4% | | 4 | 20.3 | 19.2 | -1% | | 5 | 73.3 | 68.9 | -2% | | 6 | 143.9 | 137.0 | -1% | | 7 | 285.4 | 264.3 | -3% | | 8 | 567.5 | 529.9 | -3% | | 9 | 850.0 | 819.8 | 1% | | 10 | 1132.4 | 1089.9 | 1% | | 11 | 2262.1 | 2262.1 | 4% | The following linear regression analysis was obtained: $$ y = 0. 9 5 7 x + 0. 0 3 7 $$ The linearity study results support the sponsor's claimed measuring range of 6.3 to $2000\mathrm{pg / mL}$ . {5} c. Traceability, Stability, Expected values (controls, calibrators, or methods): Traceability: The ADVIA Centaur Intact PTH assay is traceable to internal standards prepared with purified human PTH (1-84). Anchor standards are used to assign gold standards, which are manufactured using the same formulation as the anchor standards. Gold standards are then used to assign working standards. Working standards are used to value assign each lot of reagent calibrators. Value assignment of calibrators: The value assignment of calibrators is performed during Master Curve runs since the calibrators are lot specific. Calibrator value assignment is a full-curve value assignment using working standards for calibration. Four (4) different instruments, 3 runs, and 6 replicates per run are used. For new calibrators, mean concentrations across all lots and runs and repeatability pooled across all runs per reagent lot must meet internal specifications. Once the calibrators are value assigned, performance confirmation steps are executed to ensure that internal specifications for release are met. The target values for the kit calibrators are approximately 30 pg/mL and 1,630 pg/mL. Stability: The calibrator stability testing protocols and acceptance criteria were reviewed and found to be acceptable. Stability information for calibrator materials can be found in the following table: | Shelf-life | 14 months at 2-8°C | | --- | --- | | Open, reconstituted, stored at room temperature | 8 hours | | Open, reconstituted, stored at ≤ -20°C | 60 days | | On board the analyzer | 8 hours | d. Detection limit: The Limit of Blank (LoB) was determined in accordance with CLSI EP17-A2. Duplicates of each of 5 blank human samples (3 serum, 2 EDTA plasma) were measured over 2 runs per day and 3 days using 2 instruments and 3 reagent lots for a total of 120 replicates per reagent lot. The LoB was calculated non-parametrically by using the 95th percentile of 120 ranked observations for each lot. The Limit of Detection (LoD) was determined in accordance with CLSI EP17-A2 using a non-parametric approach. Eight (8) replicates of each of 8 human EDTA plasma pools with a low analyte level (~3.00 pg/mL) were measured over 2 runs per day and 3 days using 2 instruments for a total of 96 replicates per sample for each of 3 reagent lots. The LoD was determined as the lowest median dose of all samples tested per lot at which at least 95% of the measurements were greater than the LoB. {6} The Limit of Quantitation (LoQ) was determined in accordance with CLSI EP17-A2. Ten (10) replicates of each of 8 human pooled EDTA plasma samples with analyte concentrations ranging from 2 to 12 pg/mL were tested over 2 runs per day and 3 days using 1 instrument and 3 reagent lots for a total of 60 replicates per reagent lot. The LoQ was determined as the lowest concentration of PTH that can be detected at a total CV of 20%. The following detection limit claims were made: | LoB | LoD | LoQ | | --- | --- | --- | | 1.5 pg/mL | 3.2 pg/mL | 4.6 pg/mL | The measuring range of the assay is 6.3 to 2000 pg/mL. e. Analytical specificity: Interference: Interference testing was performed in accordance with CLSI EP07-A2. Two EDTA plasma pools were spiked with PTH 1-84 antigen to concentrations of 75 pg/mL and 600 pg/mL. The high PTH sample (spiked with interferent stock solution) and the low PTH sample were mixed to create intermediate levels of interferent. Samples were tested in replicates of 6. Percent interference was calculated using the following equation: $$ \% \text{Interference} = 100 \times \left( \frac{\text{Observed dose of spiked sample} - \text{Observed dose of unspiked sample}}{\text{Observed dose of unspiked sample}} \right) $$ Interference was defined by the sponsor as >10% difference from the control sample. The interference study results are summarized in the following table: | Potential interferent | Highest test concentration that demonstrated no significant interference | | --- | --- | | Hemoglobin | 500 mg/dL | | Triglycerides | 3275 mg/dL | | Bilirubin (unconjugated) | 60 mg/dL | | Bilirubin (conjugated) | 60 mg/dL | | Biotin | 1000 ng/mL | | Cholesterol | 500 mg/dL | | Total Protein | 12 g/dL | | IgG | 6 g/dL | | Calcitrol | 360 pg/mL | | Furosemide | 181 μmol/L | | Caffeine | 308 μmol/L | | Aliskiren | 200 μg/L | | Enalaprilat | 0.86 μmol/L | | Epoetin alfa | 15 mU/L | {7} | Potential interferent | Highest test concentration that demonstrated no significant interference | | --- | --- | | Fosrenol | 20 ng/mL | Human anti-mouse antibody (HAMA) interference: A HAMA interference study was performed by spiking four HAMA positive serum samples and four HAMA positive EDTA samples with synthetic PTH 1-84 to a final PTH concentration of approximately 60 and 350 pg/mL. Testing was performed on one analyzer with one lot of reagent. Percent recovery was calculated by comparing the observed PTH values from spiked HAMA positive samples to the expected PTH concentrations (based on adding a known amount of PTH). The HAMA interference study results are summarized in the table below: | | Low PTH Sample | | | High PTH Sample | | | | --- | --- | --- | --- | --- | --- | --- | | HAMA positive sample | Observed PTH (pg/mL) | Expected PTH (pg/mL) | Recovery (%) | Observed PTH (pg/mL) | Expected PTH (pg/mL) | Recovery (%) | | 1 | 56.46 | 63.48 | 89.0 | 339.12 | 344.62 | 98.4 | | 2 | 55.48 | 61.10 | 91.0 | 329.08 | 342.25 | 96.2 | | 3 | 68.97 | 66.80 | 103.2 | 356.22 | 347.94 | 102.4 | | 4 | 51.47 | 58.17 | 88.5 | 334.62 | 339.32 | 98.6 | | 5 | 56.81 | 58.38 | 97.3 | 340.48 | 339.32 | 100.3 | | 6 | 58.12 | 58.28 | 99.7 | 343.01 | 339.43 | 101.1 | The sponsor includes the following limitation in the assay package insert: "Patient samples may contain heterophilic antibodies that could react in immunoassays to give falsely elevated or depressed results. This assay is designed to minimize interference from heterophilic antibodies." Cross-reactivity: Cross-reactivity was determined by spiking each cross-reactant into human EDTA plasma containing endogenous intact PTH ( $\sim 30$ pg/mL). Percent cross-reactivity was calculated using the following equation: $\%$ Cross-reactivity $= 100 \times$ ((Concentration of cross-reactant sample - Concentration of control sample)) / Concentration of cross-reactant The cross-reactivity study results are summarized in the following table: | Cross-reactant | Concentration tested (pg/mL) | % Cross-reactivity | | --- | --- | --- | | PTH 39-68 | 100,000 | 0.0000% | | PTH 39-84 | 100,000 | 0.0004% | | Calcitonin | 100,000 | 0.0001% | | PTH 44-68 | 100,000 | 0.0003% | {8} 9 | Cross-reactant | Concentration tested (pg/mL) | % Cross-reactivity | | --- | --- | --- | | PTH-RP (1-34) | 100,000 | 0.0002% | | PTH 7-84 | 300 | 37.4% | | PTH 53-84 | 100,000 | -0.0009% | | PTH 1-34 | 12,000 | 0.0007% | | Beta-Cross Laps | 10,000 | -0.0075% | | Osteocalcin | 50,000 | -0.0003% | Hook Effect Study: To evaluate the potential for a high dose hook effect in the ADVIA Centaur Intact PTH assay, a concentrated PTH sample was prepared by spiking a EDTA plasma sample with synthetic human PTH for a final target concentration of 400,000 pg/mL. The sample was serially diluted using a Siemens Multi-diluent to obtain 11 PTH samples ranging from 391 to 400,000 pg/mL. The samples were tested in triplicate on 2 ADVIA Centaur XP systems using 2 reagent lots. The study results demonstrated that patient samples with intact PTH levels as high as 400,000 pg/mL are not affected by a high dose hook effect. The sponsor includes the following statement in the labeling regarding hook effect: “Patient samples with high intact PTH levels can cause a paradoxical decrease in the RLUs (high-dose hook effect). In this assay, patient samples with intact PTH levels as high as 100,000 pg/mL (10,600 pmol/L) are reported as >2000 pg/mL (>212 pmol/L).” f. Assay cut-off: Not applicable. 2. Comparison studies: a. Method comparison with predicate device: A method comparison study comparing the ADVIA Centaur Intact PTH assay to the predicate device (ADVIA Centaur iPTH assay) was conducted in accordance with CLSI EP09-A3. A total of 349 fresh EDTA plasma samples, ranging from 6.72 pg/mL to 1873.71 pg/mL, from apparently healthy individuals, renal dialysis patients, chronic kidney disease patients, hypoparathyroidism patients, hyperparathyroidism patients, and hypercalcemia of malignancy patients were tested in singlicate over multiple days on a total of two ADVIA Centaur XP systems. Passing & Bablok regression procedures were performed and the results are summarized below. | n | Slope | Intercept (pg/mL) | Correlation Coefficient (r) | Sample range tested (pg/mL) | | --- | --- | --- | --- | --- | | 349 | 1.02 | -2.182 | 0.99 | 6.72 to 1873.71 | {9} # b. Matrix comparison: A matrix comparison study was conducted in accordance with CLSI EP09-A3. A total of 56 paired K2-EDTA plasma (reference), serum, serum separator tube (SST) serum, lithium-heparin plasma, and sodium heparin-plasma samples were tested in triplicate each day over 8 days on one ADVIA Centaur XP system using 2 reagent lots. Passing & Bablok linear regression analysis was performed using the first individual results of the K2-EDTA plasma samples (reference matrix) and the serum, lithium heparin and sodium heparin plasma results. The results are summarized in the table below: | Comparison | Regression Equation | R | | --- | --- | --- | | K2-EDTA plasma vs. Serum | y = 0.99x - 1.85 | 0.996 | | K2-EDTA plasma vs. SST serum | y = 1.03x + 0.20 | 0.996 | | K2-EDTA plasma vs. Lithium-Heparin plasma | y = 0.99x + 1.95 | 0.998 | | K2-EDTA plasma vs. Sodium-Heparin plasma | y = 1.00x + 1.03 | 0.997 | The study results support the sponsor's claim that human serum and plasma (EDTA, lithium heparin, sodium heparin) are acceptable sample types to be used with this assay. # 3. Clinical studies: a. Clinical Sensitivity: Not applicable. b. Clinical specificity: Not applicable. c. Other clinical supportive data (when a. and b. are not applicable): Intra-Operative Clinical Study: An intra-operative clinical study was conducted to establish the intra-operative claims of the ADVIA Centaur Intact PTH assay. EDTA plasma from 30 subjects (ages 38-79 years) with primary hyperparathyroidism that met the inclusion criteria were assessed in singlicate using the ADVIA Centaur Intact PTH assay versus a comparator PTH assay FDA-cleared for intra-operative use (i.e. Siemens Immulite iPTH, Siemens OR Immulite, Siemens Immulite PTH, or Roche e411 iPTH). Intraoperative equivalence was assessed as the percentage of surgeries that were deemed either successful by the Miami criterion on both devices, or unsuccessful on both devices. The Miami {10} criterion for a successful surgery is defined to be a 50% or greater drop in intact PTH level from the greater of the pre-incision or pre-excision baseline values to the 10 minute post-excision test result after the last parathyroid gland excision. Data analysis of positive and overall percent agreements was determined in accordance with CLSI EP12-A2. Positive agreement is defined as the number of successful surgeries on both devices relative to the number of successful surgeries on the comparator devices. The overall agreement is defined as the sum of the number of successful surgeries on both devices and the number of unsuccessful surgeries on both devices relative to the total number of surgeries conducted. Successful agreement between the ADVIA Centaur Intact PTH assay and the comparator assays is defined as ≥ 85% positive percent agreement and ≥ 85% overall percent agreement. The results of the study are shown in the table below. | | Comparator assay | | | | --- | --- | --- | --- | | | | Successful surgery | Unsuccessful surgery | | ADVIA Centaur | Successful surgery | 29 | 1 | | Intact PTH assay | Unsuccessful surgery | 0 | 0 | Positive Agreement = 100% (29/29) Overall Agreement = 96.7% (29/30) This intra-operative clinical study comparing the ADVIA Centaur intact PTH assay to comparator assay methods supports the intra-operative claims of the ADVIA Centaur Intact PTH assay. 4. Clinical cut-off: Not applicable. 5. Expected values/Reference range: The reference range was assessed in accordance with CLSI EP28-A3c using 142 fresh, paired serum and EDTA plasma samples from apparently healthy donors (70 females aged 22-76 years; 72 males aged 22-65 years) with normal calcium, TSH, creatinine, and Vitamin D levels. Samples were analyzed in singlicate with one ADVIA Centaur XP system and one reagent lot. The results of the reference range study are shown below. | Sample type | 95% Reference interval (pg/mL) | Overall range (pg/mL) | | --- | --- | --- | | Plasma | 18.4 – 80.1 | 10.7 – 84.6 | | Serum | 18.5 – 88.0 | 11.2 – 99.4 | N. Proposed Labeling: The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10. {11} O. Conclusion: The submitted information in this premarket notification is complete and supports a substantial equivalence decision. 12