DIAZYME LIQUID STABLE ENZYMATIC POTASSIUM ASSAY KIT, MODEL DZ113C-X, DIAZYME LIQUID STABLE ENZYMATIC POTASSIUM ASSAY CAL
Device Facts
| Record ID | K091455 |
|---|---|
| Device Name | DIAZYME LIQUID STABLE ENZYMATIC POTASSIUM ASSAY KIT, MODEL DZ113C-X, DIAZYME LIQUID STABLE ENZYMATIC POTASSIUM ASSAY CAL |
| Applicant | Diazyme Laboratories |
| Product Code | MZV · Clinical Chemistry |
| Decision Date | Aug 14, 2009 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 862.1600 |
| Device Class | Class 2 |
Indications for Use
For in vitro quantitative determination of potassium in human serum. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels. For IVD use only. Calibrator: The Diazyme Liquid Stable Enzymatic Potassium Assay Calibrator Kit is intended for use in the calibration of quantitative Diazyme Liquid Stable Enzymatic Potassium Assay Kit (DZ113C). For IVD use only. Controls: The Diazyme Liquid Stable Enzymatic Potassium Assay Control Kit is intended for use as quality controls for the Diazyme Liquid Stable Enzymatic Potassium Assay (DZ113C). For IVD use only.
Device Story
Diazyme Liquid Stable Enzymatic Potassium Assay Kit is an in vitro diagnostic reagent system for quantitative measurement of potassium in human serum. Device utilizes enzymatic methodology to determine potassium concentration; results assist clinicians in monitoring electrolyte balance and diagnosing/treating conditions associated with hypo- or hyperkalemia. Intended for professional use in clinical laboratory settings. System includes assay reagents, calibrators, and controls to ensure measurement accuracy and quality control. Output is a quantitative potassium value used by healthcare providers to inform clinical decision-making regarding patient electrolyte management.
Clinical Evidence
Bench testing only. Precision evaluated per CLSI EP5-A2 (n=80, %CV 1.12-1.20% within-run). Linearity confirmed 2.0-8.0 mmol/L (R^2=0.9961). LOD determined as 0.87 mmol/L. Analytical specificity tested against endogenous interferents (triglycerides, hemoglobin, bilirubin, ascorbic acid) and various cations (NH4+, Pi, Ca2+, Na+, Cu2+, Fe3+, Zn2+) with no interference observed <10%. Method comparison study against predicate (n=52) yielded y = 1.0703x - 0.3042 (r=0.9805).
Technological Characteristics
Two-reagent enzymatic kit. Reagent 1: Lactate Dehydrogenase, substrate, NADH analog, lithium azide. Reagent 2: Pyruvate kinase, lithium azide. Sensing principle: spectrophotometric kinetic coupling assay. Form factor: liquid reagents, lyophilized controls. Connectivity: designed for Olympus AU400 clinical chemistry analyzers. Standards: CLSI EP5-A2, EP6-A, EP17-A, EP7-A2.
Indications for Use
Indicated for in vitro quantitative determination of potassium in human serum to monitor electrolyte balance in patients with conditions characterized by abnormal blood potassium levels.
Regulatory Classification
Identification
A potassium test system is a device intended to measure potassium in serum, plasma, and urine. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels.
Predicate Devices
- Liquid Stable Enzymatic Potassium Assay (K072665)
Related Devices
- K053566 — MODIFICATION TO: DIAZYME POTASSIUM ENZYMATIC ASSAY, MODEL DZ113A · Diazyme Laboratories · Feb 15, 2006
- K043267 — POTASSIUM TEST KIT AND ELECTROLYTE CAL 1 AND 2 · Randox Laboratories, Ltd. · Feb 10, 2005
- K082763 — DIAZYME LIQUID STABLE ENZYMATIC SODIUM ASSAY, MODEL DZ114B · Diazyme Laboratories · Nov 12, 2008
Submission Summary (Full Text)
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# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY ASSAY ONLY TEMPLATE
A. 510(k) Number:
k091455
B. Purpose for Submission:
New device
C. Measurand:
Potassium
D. Type of Test:
Quantitative, Enzymatic assay
E. Applicant:
Diazyme Laboratories
F. Proprietary and Established Names:
Diazyme Liquid Stable Enzymatic Potassium Assay Kit
Diazyme Liquid Stable Enzymatic Potassium Assay Calibrator Kit
Diazyme Liquid Stable Enzymatic Potassium Assay Controls
G. Regulatory Information:
| Product Code | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| Potassium (MZV) | Class II | 21 CFR 862.1600
Potassium test system | Clinical Chemistry (75) |
| Product Code | Classification | Regulation Section | Panel |
| Calibrator (JIT) | Class II | 21 CFR 862.1150
Calibrator | Clinical Chemistry (75) |
| Product Code | Classification | Regulation Section | Panel |
| Controls (JJX) | Class I, reserved | 21 CFR 862.1660
Quality control material (assayed and unassayed) | Clinical Chemistry (75) |
H. Intended Use:
1. Intended use(s):
Refer to Indications for use below.
2. Indication(s) for use:
Diazyme Liquid Stable Enzymatic Potassium Assay Kit
For in vitro quantitative determination of potassium in human serum. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels.
For In Vitro Diagnostic use only.
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Calibrators
The Diazyme Liquid Stable Enzymatic Potassium Assay Calibrator Kit is intended for use in the calibration of quantitative Diazyme Liquid Stable Enzymatic Potassium Assay Kit (DZ113C). For In Vitro Diagnostic use only.
Controls
The Diazyme Liquid Stable Enzymatic Potassium Assay Control Kit is intended for use as quality controls for the Diazyme Liquid Stable Enzymatic Potassium Assay (DZ113C). For In Vitro Diagnostic use only.
3. Special conditions for use statement(s):
For Prescription use only
4. Special instrument requirements:
To be used with Olympus AU400 analyzers.
I. Device Description:
The device is supplied as ready-to-use, two-reagent kit. Reagent 1 contains Lactate Dehydrogenase, substrate, NADH analog, lithium azide, and stabilizers, while reagent bottle 2 contains Pyruvate kinase, lithium azide, and stabilizers.
Ready-to-use liquid calibrators at two levels of (3.04 and 7.69 mM) are provided with the device.
Two levels of lyophilized controls (expected range: 04.46±0.67 for Control 1; 6.86±1.03 mM for Control 2) for validating the performance of the potassium reagents are sold separately.
Potassium controls are human serum based and were tested and found negative for HIV1, HIV2, HBV, and HCV using FDA approved methods
J. Substantial Equivalence Information:
1. Predicate device name(s):
Easylyte Sodium/Potassium/Lithium Analyzer
2. Predicate 510(k) number(s):
k914810
3. Comparison with predicate:
| Characteristics | New Device (k091455) Diazyme Liquid Stable Potassium Enzymatic Assay Kit | Predicate Device (k914810) Easylyte sodium/potassium/lithium Analyzer |
| --- | --- | --- |
| Type of test | Spectrophotometry; Quantitative | Ion selective electrode technology; Quantitative |
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| Characteristics | New Device (k091455)
Diazyme Liquid Stable
Potassium Enzymatic
Assay Kit | Predicate Device (k914810)
Easylyte
sodium/potassium/lithium
Analyzer |
| --- | --- | --- |
| Intended Use
(Reagent) | For in vitro quantitative determination of potassium in human serum.
Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels. For IVD use only. | The EasyLyte is an automated, microprocessor-controlled analyzer for measurement of sodium, potassium, chloride, calcium and pH in serum, plasma, whole blood and urine (urine results on Na/K, Na/K/Cl and Na/K/Li only) |
| Measuring Range | 2.0-8.0 mmol/L | 0.4 – 7.5 mmol/L |
| Specimen Type | Human serum | Human serum, plasma or whole blood |
| Controls | Lyophilized powder | Liquid |
| Calibrators | 2 levels in liquid form | Automatic on-demand ISE |
K. Standard/Guidance Document Referenced (if applicable):
- CLSI EP5-A2: Evaluation of Precision Performance of Clinical Chemistry Devices; Approved Guideline Vol 19, No 2.
- CLSI EP6-A: Evaluation of the Linearity of Quantitative Analytical Measurement Procedure: A Statistical Approach; Approved Guideline, Vol 23 No 16.
- CLSI EP17-A: Protocol for Determination of Limits of Detection and Limits of Quantitation; Approved Guideline. Vol 24, No 34.
- CLSI EP7-A2: Interference Testing in Clinical Chemistry: Approved Guideline-Second Edition.
L. Test Principle:
Potassium is determined spectrophotometrically through a kinetic coupling assay system using potassium dependent pyruvate kinase. Pyruvate generated is converted to lactate accompanying conversion of NADH analog to NAD analog. The corresponding decrease of optical density at 380nm is proportional to the potassium concentration in the serum.
M. Performance Characteristics (if/when applicable):
1. Analytical performance:
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# a. Precision/Reproducibility:
Following CLSI EP5-A, the sponsor evaluated the precision using two serum based control materials, at 4.62, and $6.96\mathrm{mM}$ Potassium, assayed in duplicate, 2 runs per day for 20 days $(n = 80)$ . The results are tabulated below.
| Sample mM | N | Mean (mM) | Within Run | | Total | |
| --- | --- | --- | --- | --- | --- | --- |
| | | | SD | %CV | SD | %CV |
| Level 1 (4.62) | 80 | 4.62 | 0.052 | 1.12 | 0.081 | 1.77 |
| Level 2 (6.96) | 80 | 6.96 | 0.084 | 1.20 | 0.122 | 1.77 |
# b. Linearity/assay reportable range:
This assay has a claimed range of $2.0 - 8.0\mathrm{mmol / L}$ . The sponsor conducted studies on the Olympus AU400 instrument to evaluate the dilution linearity of the potassium assay, using CLSI Document EP6-A as a guide. Two samples were prepared from defibrinated, delipidized human serum and a potassium stock solution to create potassium concentrations of 2.0 and $8.0\mathrm{mmol / L}$ . These two samples were mixed to create nine intermediate levels.
The linear regression analysis generated the equation, $y = 1.0271x - 0.1502$ with regression coefficient $(\mathbb{R}^2)$ of 0.9961. The results of the study support the sponsor's claimed that the assay is linear from 2.0 to $8.0\mathrm{mmol / L}$ .
# c. Traceability, Stability, Expected values (controls, calibrators, or methods):
Traceability of potassium calibrator: The calibrator is a ready-to-use liquid, including two different levels of concentrations of potassium in two separate vials. The value of the calibrator is traceable to an in-house calibration procedure that used the predicate device for value assignment.
Stability of the calibrators and controls: Real time stability studies have been conducted and are still on-going. Protocols and acceptance criteria were described and found to be acceptable. The sponsor claimed that reagents including calibrators were stable for at least 10 days at $37^{\circ}\mathrm{C}$ , 21 days at $25^{\circ}\mathrm{C}$ and 12 months when stored at 2-8 $^\circ \mathrm{C}$ . The on-board stability of the reagent is 14 days when stored at $2 - 8^{\circ}\mathrm{C}$ . The shelf-life of the controls would be 18 months when stored at $2 - 8^{\circ}\mathrm{C}$ . Once reconstituted, the controls are stable for 16 days when stored at $37^{\circ}\mathrm{C}$ .
# d. Limit of Detection:
To demonstrate the lower limit of the assay range, the sponsor performed the limit of detection (LOD) and limit of blank (LOB) tests following CLSI document EP17-A. LOB tests were conducted using blank samples conducted over a day using 3 runs with 20 replicates for each run. For LOD studies, five serum samples were selected and diluted to obtain lower concentrations and the samples were run over one day with 3 runs and 4 replicates per run for a total of 60 total replicates. Tests were run on Olympus AU400 System. Based on 12 replicates of a zero calibrator, LOB was
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determined to be $0.79\mathrm{mmol / L}$ and using this value, LOD was determined to be 0.87 mmol/L.
# e. Analytical specificity:
The sponsor evaluated the effect of known endogenous interferents on potassium assay in Olympus AU400 System using serum samples at two potassium levels. The interferents were tested at five levels and the test range included triglycerides (0-1000 mg/dL), hemoglobin (0-500 mg/dL), free bilirubin (0-20 mg/dL), bound bilirubin (0-20 mg/dL), and ascorbic acid (0-10 mM/L). The low and high potassium serum samples were spiked with varied concentrations of interfering substances and the results compared to the potassium samples without added interferant. The sponsor defined noninterference as $< 10\%$ deviation from the un-spiked samples. Based on data, the sponsor claims no interference for the substances and concentrations listed in the table below:
| Interference | Concentration |
| --- | --- |
| Ascorbic Acid | 10 mM |
| Bilirubin | 15 mg/dL |
| Bilirubin Conjugate | 20 mg/dL |
| Hemoglobin | 500 mg/dL |
| Triglyceride | 1000 mg/dL |
To determine the level of interference from other cations and substances normally present in the serum, potassium serum based control pools concentrations of 4.2 and $6.4\mathrm{mM}$ were spiked with various concentrations of cations and compared to the same control pools without added cation. Based on the sponsor's definition of interference (greater than $\pm 10\%$ of non-interfered value), the sponsor claims no interference for the cations and concentrations listed in the table below:
| Interference | Concentration |
| --- | --- |
| NH4+ | 0.5 mM |
| Pi | 2.0 mM |
| Ca2+ | 7.5 mM |
| Na+ | 150 mM |
| Cu2+ | 0.5 mM |
| Fe3+ | 0.5 mM |
| Zn2+ | 0.5 mM |
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f. Assay cut-off:
Not Applicable.
2. Comparison studies:
a. Method comparison with predicate device:
To demonstrate the substantial equivalence to the predicate device, EasyLyte ISE Na/K/Li instrument (K914810) method, the sponsor conducted a method comparison study using Olympus AU400 System. A total of 52 unaltered serum samples (range: 2.7-7.7 mM/L) were used for this study. Linear regression analysis of the data generated produced the regression equation $$y = 1.0703x - 0.3042$$ with correlation (r) of 0.9805. The analysis of data using Passing & Bablok method generated regression equation $$y = 1.0769x - 0.3577$$ with 95% CI of -0.550 to -0.1893 for intercept and 95% CI of 1.0357 to 1.1250 for the slope.
b. Matrix comparison:
Not Applicable.
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):
4. Clinical cut-off:
Not Applicable.
5. Expected values/Reference range:
The expected values of extracellular potassium levels were based on literature*. The expected value is 3.5 - 5.5mM. However, the sponsor recommends each laboratory should establish a range of normal values for the population in their region.
* Wu, A.H.B., ed. Tietz clinical guide to laboratory tests, 4th edition, p. 880. W.B. Saunders Company, St. Louis (2006).
N. Proposed Labeling:
The labeling is sufficient and it satisfies the requirements of 21 CFR Part 809.10.
O. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
