← Product Code [CEM](/submissions/CH/subpart-b%E2%80%94clinical-chemistry-test-systems/CEM) · K042270

# STAT K IN VITRO DIAGNOSTIC TEST SYSTEM (K042270)

_Stat Chem, Inc. · CEM · Oct 6, 2004 · Clinical Chemistry · SESE_

**Canonical URL:** https://fda.innolitics.com/submissions/CH/subpart-b%E2%80%94clinical-chemistry-test-systems/CEM/K042270

## Device Facts

- **Applicant:** Stat Chem, Inc.
- **Product Code:** [CEM](/submissions/CH/subpart-b%E2%80%94clinical-chemistry-test-systems/CEM.md)
- **Decision Date:** Oct 6, 2004
- **Decision:** SESE
- **Submission Type:** Traditional
- **Regulation:** 21 CFR 862.1600
- **Device Class:** Class 2
- **Review Panel:** Clinical Chemistry
- **Attributes:** Pediatric

## Indications for Use

The StatChem Stat K is a device intended to measure potassium in anticoagulated venous whole blood and assayed within twenty minutes. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of disease conditions characterized by low or high blood potassium levels. The Stat K may be used for adult or pediatric venous whole blood samples. It may be used by a central laboratory or at point of care sites.

## Device Story

Stat K is a battery-operated, handheld in vitro diagnostic analyzer for measuring potassium in venous whole blood. The system uses disposable, precalibrated, liquid-free sensor cartridges containing a Valinomycin-based ion-selective membrane. Operation involves four steps: inserting the cartridge, peeling the cap, applying a blood sample, and reading results on an LCD. The device uses an ion-selective membrane to bind potassium ions, generating an electrical potential proportional to the logarithm of the ion concentration; the concentration is calculated via the Nernst Equation. Calibration occurs automatically before each test using a predetermined concentration of potassium within the sensor. Used by clinicians at point-of-care sites or central laboratories to monitor electrolyte balance, the output provides immediate potassium levels to assist in clinical decision-making for patients with suspected electrolyte imbalances.

## Clinical Evidence

Bench testing only. Precision performance evaluated using aqueous solutions and venous whole blood per NCCLS EP5-A. Method comparison conducted against Corning 614 and Beckman Coulter SYNCRON CX5 PRO. Linear regression results: Stat K = 0.12 + 0.97 Corning 614; Stat K = 0.08 + 1.02 Beckman CX5. Data indicate substantial equivalence to predicate devices.

## Technological Characteristics

Handheld, battery-operated analyzer. Sensing principle: electrochemical ion-selective electrode using Valinomycin-embedded plastic polymer membrane. Calibration: factory-precalibrated, single-use disposable cartridges. Output: LCD display. System control: microprocessor-based. Temperature compensated. No external connectivity mentioned.

## Regulatory 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

- Stat K System ([K915345](/device/K915345.md))
- SYNCHRON CX5 SYSTEM ([K011465](/device/K011465.md))
- Corning 614 Na/K Analyzer ([K843530](/device/K843530.md))

## Submission Summary (Full Text)

> This content was OCRed from public FDA records by [Innolitics](https://innolitics.com). If you use, quote, summarize, crawl, or train on this content, cite Innolitics at https://innolitics.com.
>
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510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION
DECISION SUMMARY
DEVICE ONLY TEMPLATE

A. 510(k) Number: k042270
B. Purpose for Submission: New Device
C. Analyte: Potassium
D. Type of Test: Quantitative ion selective electrode
E. Applicant: StatChem, Inc.
F. Proprietary and Established Names: Stat K In Vitro Diagnostic Test System
G. Regulatory Information:
H. Regulation section: 21 CFR §862.1600 Potassium test system
1. Classification: Class II
2. Product Code: CEM
3. Panel: 75 (Clinical Chemistry)

I. Intended Use:
1. Intended use / Indication(s) for use: The StatChem Stat K is a device intended to measure potassium in anticoagulated venous whole blood and assayed within twenty minutes of collection. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of disease conditions characterized by low or high blood potassium levels. It may be used by a central laboratory or at point of care sites.
2. Special condition for use statement(s): Not Applicable
3. Special instrument Requirements: Not Applicable

J. Device Description:
The Stat K In Vitro Diagnostic Test System consists of a battery operated hand-held Analyzer and a precalibrated and disposable Sensor cartridge. The Sensor cartridge is liquid-free allowing storage at room temperature for several months without degradation of performance. The Sensor cartridge is precalibrated at the factory thus requiring no operator interaction to perform calibration. The Sensor cartridge is designed for single use only. This device is exceptionally simple to use as the operator is required to perform four elementary steps to complete the test: (1) Insert Sensor Cartridge, (2) Peel Sensor

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cap when prompted, (3) Apply blood sample when prompted, and, (4) Read results on LCD display.

## K. Substantial Equivalence Information:

1. Predicate device name(s): Stat K System; BECKMAN SYNCHRON CX5® PRO SYSTEM; Corning 614 Na/K Analyzer
2. Predicate K number(s): K915345 (Stat K System); K011465 (BECKMAN SYNCHRON CX5® PRO SYSTEM); K843530 (Corning 614 Na/K Analyzer)
3. Comparison with predicates:

|  Similarities (Portable Diagnostics Stat K)  |   |   |
| --- | --- | --- |
|  Item | Device | Predicate  |
|  Methodology | Same | Ion-Selective Electrode  |
|  Power Source | Same | Battery Operated  |
|  Hand held | Same | Yes  |
|  Temperature Compensated | Same | Yes  |
|  System Control | Same | Microprocessor  |
|  Calibration Membrane | Same | Gel based  |
|  Measuring Range | Same | 2.0 – 8.0 mEq/L  |
|  Differences (Portable Diagnostics Stat K)  |   |   |
|  Item | Device | Predicate  |
|  Specimen Type | Venous Whole Blood | Whole Blood, Serum or Plasma  |
|  Analyzer/Cartridge Interface | Semiconductor Element | Bar Code  |
|  Sensing Membrane | Plastic Polymer | Gel based  |
|  Similarities (CORNING 614 NA/K ANALYZER)  |   |   |
| --- | --- | --- |
|  Item | Device | Predicate  |
|  Methodology | Same | Ion-Selective Electrode  |
|  Temperature Compensated | Yes | Yes  |
|  System Control | Microprocessor | Microprocessor  |
|  Precision Claims | Within-run CV ≤ 3.0% (Whole Blood) | Within-run CV ≤ 1.5% (Whole Blood)
Between-run CV ≤ 2.0% (Whole Blood)  |
|   |  Total Precision CV ≤ 2.0% (aqueous potassium solution) | No Claims Made  |
|  Differences (CORNING 614 NA/K ANALYZER)  |   |   |
|  Item | Device | Predicate  |
|  Analyte(s) | Potassium | Multiple Analytes  |
|  Measuring Range | 2.00 – 8.00 mEq/L | 0.50 – 9.99 mEq/L  |
|  Specimen Type | Venous Whole Blood | Whole Blood, Serum, or Urine  |
|  Power Source | Battery Operated | Alternating Current  |
|  Display | Liquid Crystal | Vacuum Fluorescent Display  |
|  Analyzer/Cartridge Interface | Semiconductor Element | Does not apply  |
|  Sensing Membrane | Plastic Polymer | Solvent based  |
|  Calibration Membrane | Gel based | None  |
|  Single Use | Yes | Batch  |

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## L. Standard/Guidance Document Referenced (if applicable):

FDA Guidance for the content of Pre-market Submissions for Software Contained in Medical Devices, issued May 29, 1998; IEC 61010 Safety Requirements for Electrical Equipment for Measurement, Control, and Laboratory Use; NCCLS EP5-A Evaluation of Precision Performance of Clinical Chemistry Devices; NCCLS EP9-A2 Method Comparison and Bias Estimation Using Patient Samples

## M. Test Principle:

The Stat K Potassium Sensor uses an ion selective membrane to determine the concentration of potassium ions in solution. The physical structure of the potassium selective Valinomycin membrane is such that the complexing sites on the membrane selectively bind to Potassium ions. When complexing occurs, an electrical potential is generated proportional to the logarithm of the potassium ion concentration in the sample. The concentration of Potassium ions is calculated from the electrode potential by use of the Nernst Equation.

## N. Performance Characteristics (if/when applicable):

### 1. Analytical performance:

a. **Precision/Reproducibility**: The precision performance of this device was evaluated in two separate experiments, one using aqueous solutions with known concentrations of potassium and the other using venous whole blood.

For the aqueous samples, with-in run and total imprecision were calculated using an experimental design based on NCCLS EP5-A, Evaluation of Precision Performance of Clinical Chemistry Devices. Testing consisted of 1 run per day with 8 replicates per run for 5 days. Acceptance criteria for both within-run and total precision were established as a % coefficient of variation of 3.3% or less at potassium concentrations of 3.0 and 6.0 mEq/L. Results were as follows:

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|  Target concentration 3.0 mEq/L | Day 1 | Day 2 | Day 3 | Day 4 | Day 5  |
| --- | --- | --- | --- | --- | --- |
|  Replicate | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L)  |
|  1 | 3.05 | 3.06 | 3.00 | 2.88 | 3.01  |
|  2 | 2.92 | 3.05 | 3.03 | 2.99 | 2.98  |
|  3 | 3.00 | 3.00 | 3.01 | 2.90 | 3.02  |
|  4 | 3.06 | 3.00 | 2.98 | 2.99 | 2.99  |
|  5 | 2.95 | 2.99 | 2.91 | 3.13 | 3.00  |
|  6 | 2.98 | 3.03 | 2.98 | 2.87 | 3.02  |
|  7 | 3.03 | 2.95 | 2.99 | 3.00 | 2.98  |
|  8 | 2.95 | 2.99 | 2.90 | 2.99 | 2.99  |
|  Within-run imprecision (mEq/L) | 0.05  |
| --- | --- |
|  Within-run CV (%) | 1.7  |
|  Total imprecision (mEq/L) | 0.05  |
|  Total CV (%) | 1.6  |
|  Target concentration 6.0 mEq/L | Day 1 | Day 2 | Day 3 | Day 4 | Day 5  |
| --- | --- | --- | --- | --- | --- |
|  Replicate | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L)  |
|  1 | 6.09 | 6.22 | 6.01 | 6.00 | 5.89  |
|  2 | 5.82 | 6.03 | 5.99 | 6.01 | 5.98  |
|  3 | 5.82 | 6.14 | 6.02 | 5.99 | 6.04  |
|  4 | 6.13 | 5.99 | 5.81 | 5.99 | 5.96  |
|  5 | 6.14 | 5.87 | 5.94 | 5.95 | 6.15  |
|  6 | 6.01 | 5.98 | 6.02 | 5.98 | 6.07  |
|  7 | 5.99 | 5.92 | 6.00 | 5.99 | 5.99  |
|  8 | 6.10 | 5.77 | 5.99 | 6.07 | 6.15  |
|  Within-run imprecision (mEq/L) | 0.10  |
| --- | --- |
|  Within-run CV (%) | 1.7  |
|  Total imprecision (mEq/L) | 0.09  |
|  Total CV (%) | 1.6  |

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Using the venous whole blood samples, within-run imprecision was evaluated by measuring the potassium concentration in a total of 6 venous whole blood samples collected at 3 sites over 2 days. Seven replicate measurements of each sample were completed in 32 minutes or less. Acceptance criteria were established as: the average percent coefficient of variation of the six samples must be less than or equal to  $3.5\%$  with no individual CV exceeding  $4.0\%$ . Results were as follows:

|   | Site 1 Day 1 | Site 1 Day 2 | Site 2 Day 1 | Site 2 Day 2 | Site 3 Day 1 | Site 3 Day 2  |
| --- | --- | --- | --- | --- | --- | --- |
|  Rep | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L) | K Result (mEq/L)  |
|  1 | 4.02 | 4.10 | 5.71 | 2.95 | 7.06 | 6.85  |
|  2 | 3.88 | 4.34 | 5.83 | 3.04 | 6.79 | 6.98  |
|  3 | 3.98 | 4.29 | 5.90 | 2.89 | 6.87 | 6.75  |
|  4 | 3.69 | 4.21 | 5.97 | 2.99 | 6.66 | 6.61  |
|  5 | 3.90 | 4.30 | 5.90 | 2.89 | 6.61 | 7.10  |
|  6 | 3.92 | 4.10 | 5.80 | 2.92 | 6.85 | 6.86  |
|  7 | 3.91 | 4.18 | 5.99 | 2.88 | 6.81 | 6.89  |
|  Mean | 3.90 | 4.22 | 5.87 | 2.94 | 6.81 | 6.86  |
|  Std Dev | 0.10 | 0.10 | 0.10 | 0.06 | 0.15 | 0.16  |
|  CV (%) | 2.7 | 2.3 | 1.7 | 2.0 | 2.2 | 2.3  |

b. Linearity/Assay Reportable Range: The linearity of this device was established by assaying commercially available whole blood chemistry controls of known concentration. The five known concentrations were 2.10, 3.50, 5.00, 6.50, and  $7.90\mathrm{mEq / L}$ . Each sample was assayed in duplicate for a total of ten measurements. The mean of the duplicate measurements was plotted against the known concentrations and the line of best fit was calculated. Acceptable performance was established as a coefficient of determination  $(\mathrm{r}^2)$  value of  $\geq$  0.975. Results were as follows:

|  Known Concentration (mEq/L) | Replicate 1 | Replicate 2 | Mean  |
| --- | --- | --- | --- |
|  2.0 | 1.94 | 1.94 | 1.94  |
|  3.5 | 3.64 | 3.79 | 3.72  |
|  5.0 | 5.03 | 5.35 | 5.19  |
|  6.5 | 6.72 | 6.74 | 6.73  |
|  7.9 | 7.95 | 7.90 | 7.93  |

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The calculated coefficient of correlation (r) was 0.998

c. Traceability, Stability, Expected values (controls, calibrators, or method):

The sponsor has submitted the following protocol to establish the expiration dating of the Stat K sensors. Sensors will be taken from a routine production run, stored at 18 to 25 °C, and used to assay an aqueous potassium solution at 6.00 mEq/L. An analytical run is defined as eight (8) replicates of the known potassium solution. A run will be conducted at 30 day intervals beginning at day 30 and ending at day 570. Acceptable performance is defined as a coefficient of variation of ≤ 4.0% and a bias of not more than ± 0.15 mEq/L.

d. Detection limit: The lower limit of detection is 2.00 mEq/L. See section M.1.b.

e. Analytical specificity: The sponsor refers the user to the specificity testing done on the predicate device, Portable Diagnostic Services Stat K System. Users are also referred to a discussion of ion-selective electrodes in Tietz Textbook of Clinical Chemistry – Second Edition, 1994.

f. Assay cut-off: N/A

2. Comparison studies:

a. Method comparison with predicate device:

This study compared Lithium heparinized split samples on the Stat K and the Corning 614. Measurements were taken in duplicate and the mean of the measurements was used to calculate the line of best fit:

Slope = 0.97 (95% CI 0.91, 1.04)
y-intercept = 0.12 mEq/L (95% CI -0.20, 0.43)
Predicted bias at 3.36 mEq/L: 0.03 mEq/L (95% CI -0.06, 0.13)
Predicted bias at 6.00 mEq/L: -0.03 mEq/L (95% CI -0.13, 0.07)
r = 0.979
n = 40
Range of data: 3.36 – 7.27 mEq/L

b. Matrix comparison:

Not applicable. The Stat K is intended for use with venous whole blood only.

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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): Not Applicable

4. Clinical cut-off: Not Applicable

5. Expected values/Reference range:
Newborn – one month: 3.7 – 5.9 mEq/L
One month – one year: 4.1 – 5.3 mEq/L
Ages 1 – 10: 3.5 – 5.1 mEq/L
Adults: 3.8 – 5.2 mEq/L

These ranges and supportive documentation are derived from previously established literature:

B.E. Statland, Clinical Decision Levels for Lab Tests; Oradell, NJ: Medical Economic Books, 1987 and P.C. Painter, T.Y. Cope, J.L. Smith, Reference Ranges, Table 41-20, in Tietz Textbook of Clinical Chemistry – Second Edition, C.A. Burtis and E.R. Ashwood, Eds. Philadelphia: W.B. Saunders Company, 1994).

A. Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.

---

**Source:** [https://fda.innolitics.com/submissions/CH/subpart-b%E2%80%94clinical-chemistry-test-systems/CEM/K042270](https://fda.innolitics.com/submissions/CH/subpart-b%E2%80%94clinical-chemistry-test-systems/CEM/K042270)

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