ABL90 FLEX PLUS System
Device Facts
| Record ID | K252475 |
|---|---|
| Device Name | ABL90 FLEX PLUS System |
| Applicant | Radiometer Medicals Aps |
| Product Code | JGS · Clinical Chemistry |
| Decision Date | May 1, 2026 |
| Decision | SESE |
| Submission Type | Traditional |
| Regulation | 21 CFR 862.1665 |
| Device Class | Class 2 |
Indications for Use
The ABL90 FLEX PLUS System is an in vitro diagnostic, portable, automated analyzer that quantitatively measures electrolytes: cCl- in heparinized capillary, arterial and venous whole blood, and cCa2+ and cNa+ in heparinized capillary whole blood. The ABL90 FLEX PLUS System is intended for use by trained technologists, nurses, physicians and therapists. It is intended for use in a laboratory environment, near patient, or point-of-care setting. These tests are only performed under a physician's order. Calcium (cCa2+): Calcium measurements are used in the diagnosis and treatment of parathyroid disease, a variety of bone diseases, chronic renal disease and tetany. Sodium (cNa+): Sodium measurements are used in the diagnosis and treatment of aldosteronism, diabetes insipidus, adrenal hypertension, Addison's disease, dehydration, inappropriate antidiuretic secretion, or other diseases involving electrolyte imbalance. Chloride (cCl-): Chloride measurements are used in the diagnosis and treatment of electrolyte and metabolic disorders such as cystic fibrosis and diabetic acidosis.
Device Story
Portable, automated in vitro diagnostic analyzer; measures electrolytes (cCl-, cNa+, cCa2+) in heparinized whole blood samples. Operates via potentiometry using sensor cassettes and solution packs. Features automated sample inlet with three modes: S65/SP65 (venous/arterial) and C65 (capillary). Used in labs or point-of-care settings by trained clinicians (technologists, nurses, physicians, therapists). Provides quantitative electrolyte results to support clinical decision-making for metabolic, renal, and electrolyte disorders. Benefits patients through rapid, near-patient diagnostic testing.
Clinical Evidence
Bench testing only. Precision studies performed at POC sites using aqueous controls and native heparinized capillary whole blood (N=39 subjects). Linearity evaluated for cCl⁻ (R²=1.00). Interference testing conducted per CLSI EP07. Method comparison study (N≥100 samples per analyte) compared capillary whole blood results against arterial/venous comparator methods using Deming regression; results showed acceptable bias and correlation (R² 0.93-1.00).
Technological Characteristics
Potentiometric sensor-based analyzer. Consumables: sensor cassette and solution pack. Sample modes: S65, SP65, C65. Portable form factor. Connectivity/software details not specified. Sterilization method not specified.
Indications for Use
Indicated for quantitative measurement of electrolytes (cCl⁻, cCa²⁺, cNa⁺) in heparinized whole blood (arterial, venous, capillary) for patients requiring diagnosis/treatment of electrolyte/metabolic disorders, parathyroid, bone, or renal disease. For use by trained professionals in lab or point-of-care settings under physician order.
Regulatory Classification
Identification
A sodium test system is a device intended to measure sodium in serum, plasma, and urine. Measurements obtained by this device are used in the diagnosis and treatment of aldosteronism (excessive secretion of the hormone aldosterone), diabetes insipidus (chronic excretion of large amounts of dilute urine, accompanied by extreme thirst), adrenal hypertension, Addison's disease (caused by destruction of the adrenal glands), dehydration, inappropriate antidiuretic hormone secretion, or other diseases involving electrolyte imbalance.
Predicate Devices
- Stat Profile® Prime Plus Analyzer System (K200403)
Submission Summary (Full Text)
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FDA U.S. FOOD & DRUG ADMINISTRATION
# 510(k) SUBSTANTIAL EQUIVALENCE DETERMINATION DECISION SUMMARY
ASSAY ONLY
## I Background Information:
A 510(k) Number
K252475
B Applicant
Radiometer Medicals ApS
C Proprietary and Established Names
ABL90 FLEX PLUS System
D Regulatory Information
| Product Code(s) | Classification | Regulation Section | Panel |
| --- | --- | --- | --- |
| JGS | 862.1665 | Sodium Test System | CH |
| JFP | 862.1145 | Calcium Test System | CH |
| CGZ | 862.1170 | Chloride Test System | CH |
## II Submission/Device Overview:
A Purpose for Submission:
Modification to a previously cleared device.
B Measurand:
Sodium (cNa⁺), Calcium (cCa²⁺), and Chloride (cCl⁻)
C Type of Test:
Potentiometry
Food and Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993-0002
www.fda.gov
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III Intended Use/Indications for Use:
A Intended Use(s):
See Indications for Use below.
B Indication(s) for Use:
The ABL90 FLEX PLUS System is an in vitro diagnostic, portable, automated analyzer that quantitatively measures electrolytes:
- cCl⁻ in heparinized arterial, venous and capillary whole blood, and
- cCa²⁺ and cNa⁺ in heparinized capillary whole blood
The ABL90 FLEX PLUS System is intended for use by trained technologists, nurses, physicians and therapists. It is intended for use in a laboratory environment, near patient, or point-of-care setting.
These tests are only performed under a physician's order.
Calcium (cCa²⁺): Calcium measurements are used in the diagnosis and treatment of parathyroid disease, a variety of bone diseases, chronic renal disease and tetany.
Sodium (cNa⁺): Sodium measurements are used in the diagnosis and treatment of aldosteronism, diabetes insipidus, adrenal hypertension, Addison's disease, dehydration, inappropriate antidiuretic secretion, or other diseases involving electrolyte imbalance.
Chloride (cCl⁻): Chloride measurements are used in the diagnosis and treatment of electrolyte and metabolic disorders such as cystic fibrosis and diabetic acidosis.
C Special Conditions for Use Statement(s):
Rx - For Prescription Use Only
D Special Instrument Requirements:
ABL90 FLEX PLUS System
IV Device/System Characteristics:
A Device Description:
The ABL90 FLEX PLUS System consists of the ABL90 FLEX PLUS analyzer, sensor cassette (SC) and solution pack (SP) consumables, and related accessories for the analyzer as described in K240998. The ABL90 FLEX PLUS System has an automated sample inlet mechanism, which can collect arterial and venous whole blood through two different measuring modes: the S65 syringe mode and the SP65 short probe mode, and capillary whole blood through the C65 capillary mode. For the C65 modes, samples are loaded using safeCLINITUBES which are 70 and 100μL plastic capillary tubes with balanced heparin, mixing wires and end caps.
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This submission is for the addition of capillary heparinized whole blood samples for Sodium (cNa⁺) and Calcium (cCa²⁺) and for capillary, arterial and venous heparinized whole blood samples for Chloride (cCl⁻).
The ABL90 FLEX PLUS System is cleared for the quantitative measurement of pH, pO2, pCO2, oximetry (sO2, ctHb, FO2Hb, FCOHb, FMetHb, FHHb) cK⁺, cNa⁺, cCa²⁺, cGlu, and cLac using arterial and venous heparinized whole blood samples. The system is cleared for the quantitative measurement of pH, pCO2, ctHb and cGlu using capillary heparinized whole blood sample (K240998, K241037, K252207 and K252488).
## B Principle of Operation:
Potentiometry: The potential of an electrode chain is measured by a voltmeter and related to the concentration of the sample (the Nernst equation). The potentiometric measuring principle is applied in cNa⁺, cCa²⁺, and cCl⁻ sensors.
## V Substantial Equivalence Information:
## A Predicate Device Name(s):
Stat Profile® Prime Plus Analyzer System
## B Predicate 510(k) Number(s):
K200403
## C Comparison with Predicate(s):
| Device & Predicate Device(s): | K252475 | K200403 |
| --- | --- | --- |
| Device Trade Name | ABL90 FLEX PLUS System | Stat Profile® Prime Plus Analyzer System |
| General Device Characteristic Similarities | | |
| Intended Use/Indications For Use | Intended for the quantitative measurements of sodium, ionized calcium and chloride | Same |
| Intended Use Environment | Laboratory environment, near patient or point-of-care setting | Same |
| General Device Characteristic Differences | | |
| Sample Type | Heparinized capillary whole blood for cCl⁻ and heparinized arterial and venous. | Heparinized arterial and venous whole blood |
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| Device & Predicate Device(s): | K252475 | K200403 |
| --- | --- | --- |
| | venous whole blood for cCl-, cNa+, and cCa2+ | |
| Analytes | cNa+, cCa2+, and cCl- | K+, Na+, iCa2+, Cl-, iMg2+ |
# VI Standards/Guidance Documents Referenced:
Clinical and Laboratory Standards Institute (CLSI) EP05-A3 – Evaluation of Precision of Quantitative Measurement Procedures
CLSI EP09c 3rd Edition – Measurement Procedure Comparison and Bias Estimation Using Patient Samples
CLSI EP17-A2 2nd Edition – Evaluation of Detection Capability for Clinical Laboratory Measurement Procedures; Approved Guideline
CLSI EP06-2nd Edition – Evaluation of Linearity of Quantitative Measurement Procedures
CLSI EP07-3rd Edition – Interference Testing in Clinical Chemistry
CLSI EP37 1st Edition – Supplemental Tables for Interference Testing in Clinical Chemistry
CLSI EP39 1st Edition – A Hierarchical Approach to Selecting Surrogate Samples for the Evaluation of In Vitro Medical Laboratory Tests
# VII Performance Characteristics (if/when applicable):
# A Analytical Performance:
# 1. Precision/Reproducibility:
Point of care precision (aqueous control material):
A multi-day precision study was performed at one internal site using three concentrations of aqueous control solutions and three reagent lots. Each level was tested on three analyzers as two replicates per run, two runs per day, for twenty days. Repeatability, within-laboratory precision, and reproducibility results are reported below:
| Parameters (units) | QC Level | N | Mean (mmol/L) | Repeatability | | Within Lab Precision | | Reproducibility | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | | SD | CV% | SD | CV% | SD | CV% |
| cCl-(mmol/L) | L1 | 234 | 93 | 0.1 | 0.1 | 0.2 | 0.3 | 0.2 | 0.3 |
| | L2 | 234 | 99 | 0.1 | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 |
| | L3 | 240 | 140 | 0.2 | 0.1 | 0.4 | 0.3 | 0.4 | 0.3 |
A multi-day precision study was performed at three POC sites using three concentrations of aqueous control solutions and three reagent lots. At each site, each level was tested as three replicates per run, two runs per day, for at least five days. At least two POC operators were included at each site. Repeatability, within-laboratory precision, and reproducibility results are reported below:
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| Parameters (units) | QC Level | N | Mean (mmol/L) | Repeatability | | Within Lab Precision | | Reproducibility | |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| | | | | SD | CV% | SD | CV% | SD | CV% |
| cCl⁻ (mmol/L) | L1 | 101 | 93 | 0.1 | 0.1 | 0.3 | 0.4 | 0.4 | 0.4 |
| | L2 | 102 | 99 | 0.1 | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 |
| | L3 | 101 | 140 | 0.1 | 0.1 | 0.3 | 0.2 | 0.3 | 0.2 |
## Whole Blood for Chloride
Point of Care precision (Arterial and Venous Whole Blood) cCl⁻ in S65 and SP65 Mode: A multi-day precision study was performed at three POC sites by at least three POC operators at each site, using balanced heparinized whole blood targeted to levels within the reportable range of cCl⁻. The whole blood precision was assessed using duplicate test results collected across multiple point of care sites using both the S65 and SP65 sampling modes. Samples were grouped into subintervals based on their mean values. The results are summarized below.
| Parameter (mmol/L) | N | Test interval | Mean | Repeatability | |
| --- | --- | --- | --- | --- | --- |
| | | | | SD | CV% |
| S65 Mode | | | | | |
| cCl⁻ | 30 | 80 - <98 | 95.857 | 0.154 | 0.16 |
| | 108 | 98 - 107 | 103.62 | 0.124 | 0.12 |
| | 90 | >107 - <130 | 110.46 | 0.102 | 0.09 |
| | 18 | 130 - <150 | 141.59 | 0.108 | 0.08 |
| SP65 Mode | | | | | |
| cCl⁻ | 34 | 80 - <98 | 95.612 | 0.064 | 0.07 |
| | 108 | 98 - 107 | 103.62 | 0.073 | 0.07 |
| | 84 | >107 - <130 | 110.50 | 0.071 | 0.06 |
| | 18 | 130 - <150 | 141.34 | 0.058 | 0.04 |
## Capillary (C65) Mode for Calcium, Chloride, and Sodium
A precision study was performed at two POC sites with at least two POC operators in capillary (C65) mode using native heparinized capillary whole blood and two reagent lots. The study spanned 15 days, testing two subjects per day with two samples collected from each subject. A total of 39 subjects were included in the study.
| Parameter (units) | N | Test Interval | Mean | Repeatability | |
| --- | --- | --- | --- | --- | --- |
| | | | | Std | CV (%) |
| cCa²⁺ (mg/dL) | 8 | 3.4 - <4.8 | 4.677 | 0.017 | 0.35 |
| | 42 | 4.8 - <5.0 | 4.921 | 0.045 | 0.91 |
| | 28 | 5.0 - <5.812 | 5.143 | 0.074 | 1.43 |
| cCl⁻ (mmol/L) | 28 | 80 - <107 | 104.76 | 0.793 | 0.76 |
| | 26 | 107 - <110 | 108.58 | 0.803 | 0.74 |
| | 24 | 110 - <130 | 112.45 | 0.686 | 0.61 |
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| Parameter (units) | N | Test Interval | Mean | Repeatability | |
| --- | --- | --- | --- | --- | --- |
| | | | | Std | CV (%) |
| cNa⁺ (mmol/L) | 4 | 120 - <136 | 130.98 | 1.278 | 0.98 |
| | 66 | 136 - <146 | 142.25 | 0.749 | 0.53 |
| | 8 | 146 - <155 | 147.76 | 0.662 | 0.45 |
2. Linearity:
Linearity testing for cCl⁻ was conducted in general accordance with CLSI EP06-A2. The linearity of the ABL90 FLEX PLUS System for cCl⁻ measurements was evaluated by preparing heparinized venous whole blood samples at low and high concentrations. Eleven test concentrations were then generated by mixing of these high and low samples. At least 20 replicates were run for each level. The maximum deviation from linearity was -0.42%.
| Parameter (units) | Reportable Range | Tested Linearity Range | Slope | Intercept | R2 |
| --- | --- | --- | --- | --- | --- |
| cCl⁻ (mmol/L) | 86 - 151 | 70.1 - 165 | 0.998 | 1.022 | 1.00 |
Linearity for cNa⁺ and cCa²⁺ was previously established in K241037.
3. Analytical Specificity/Interference:
Interference testing for cCl⁻ was conducted in two parts: paired-difference testing and dose-response experiments and in general accordance with CLSI EP07.
a) The paired-difference testing was conducted on all potential interferents. Matched samples were tested, one with no interferent and the other with the interferent. If no interference was found, no further testing was performed.
b) The dose-response experiment was only conducted on interferents found to have an effect via the paired-difference testing. This was carried out to determine the concentration at which clinically significant interference occurred.
Freshly drawn heparinized adult venous whole blood samples were used as starting material for the interference studies. Interference testing was conducted at two cCl⁻ levels (i.e., 100 mmol/L and 110 mmol/L). The following table lists the concentrations of each substance at which no significant interference was found.
Highest concentration tested at which no significant interference is observed.
| Potential Interferent for cCl- | Concentration |
| --- | --- |
| Acetylsalicylic acid | 65 mg/dL |
| Acetyltryptophane | 3.0 mg/dL |
| Ammonium chloride | 5.3 mg/dL |
| Ascorbate (sodium-) Na salt | 392 mg/dL |
| Benzalkonium chloride | 2.4 mg/dL |
| Bicarbonate (HCO₃⁻) at low level | 42 mg/dL |
| Bicarbonate (HCO₃⁻) at high level | 378 mg/dL |
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For those substances that on initial screening were found to interfere, dose response testing was conducted to establish the concentration limit below which no significant interference is expected. The results are summarized in the table below:
| Interferent | Maximum test concentration | Highest concentration level without interference | Impact on result |
| --- | --- | --- | --- |
| cCl- (test level: 100 mmol/L) | | | |
| Bromide (sodium-) | 391 mg/dL | 24.4 mg/dL | 80.22 mmol/L |
| Iodide (sodium-) | 45 mg/dL | 11.25 mg/dL | 11.57 mmol/L |
| Perchlorate ClO4 (potassium-) | 20.8 mg/dL | 15.6 mg/dL | 6.351 mmol/L |
| pH at low level | 6.8 | Cl- is corrected for bicarbonate, calculated from pH and pCO2. pH interference on Cl sensor will also depend on pCO2 level. | 10.91 mmol/L (measured at pCO2 84 mmHg) |
| Thiocyanate (sodium-) | 195mg/dL | 3.66 mg/dL | 51.90 mmol/L |
| cCl- (test level: 110 mmol/L) | | | |
| Bromide (sodium-) | 391 mg/dL | 24.4 mg/dL | 80.23 mmol/L |
| Iodide (sodium-) | 45 mg/dL | 11.25 mg/dL | 12.12 mmol/L |
| Perchlorate ClO4 (potassium-) | 20.8 mg/dL | No interference | N/A |
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| Interferent | Maximum test concentration | Highest concentration level without interference | Impact on result |
| --- | --- | --- | --- |
| pH at low level | 6.8 | Cl⁻ is corrected for bicarbonate, calculated from pH and pCO₂. pH interference on Cl sensor will also depend on pCO₂ level. | 9.93 mmol/L (measured at pCO₂ 108 mmHg) |
| Thiocyanate (sodium-) | 195 mg/dL | 4.88 mg/dL | 58.746 mmol/L |
The sponsor included the following in their labeling:
The chloride measurement is corrected for bicarbonate, calculated from pH and pCO₂. There is no indication of clinically significant interference at pH above 7.1. The combination of very low pH and very high pCO₂ level may interfere with the chloride measurements. Clinically significant interference has been observed at pH 6.8 and pCO₂ levels around 100 mmHg. For pH measurements below 7.1, it is recommended to always interpret results of chloride in conjunction with the other measurements reported by the ABL90 FLEX PLUS analyzer and the overall clinical context.
4. Assay Reportable Range:
The reportable range for cCl⁻ is 86 – 151 mmol/L. The reportable ranges for cNa⁺ and cCa²⁺ were previously established in K241037.
5. Traceability, Stability, Expected Values (Controls, Calibrators, or Methods):
cCl⁻ is traceable to SRM999 NIST Standard Reference Material. Refer to K241037 for traceability information for cNa⁺ and cCa²⁺.
6. Detection Limit:
Detection capability for limit of quantitation (LoQ) was conducted in general accordance with CLSI EP17-A2. Testing was performed using 4 independent heparinized venous whole blood samples, three reagent lots, nine instruments, over the course of nine days, with at least 5 replicates/sample, and 60 replicates/reagent lot, using the S65 mode.
| Parameter | Unit | LoQ |
| --- | --- | --- |
| cCl⁻ | mmol/L | 77 |
B Comparison Studies:
1. Method Comparison with Predicate Device:
Method comparison studies were conducted in general accordance with CLSI EP09c-ED3.
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Method comparison for $\mathrm{cCl^-}$ using heparinized arterial and venous whole blood specimens in S65 and SP65 mode and for $\mathrm{cNa^{+}}$ , $\mathrm{cCa^{2+}}$ , and $\mathrm{cCl^-}$ in heparinized capillary whole blood samples in C65 mode on the ABL90 FLEX PLUS System was done in general accordance with CLSI EP09c-ED3. A minimum of 100 heparinized arterial (A), venous (V), and capillary whole blood specimens (maximum of $10\%$ contrived) were collected across 3 POC sites by at least 2 operators per site. Capillary blood samples were collected in 2 safeCLINITUBE capillary tubes and were compared to venous and arterial whole blood specimens tested on a comparator method. Specifically, each capillary whole blood sample was measured once on the candidate device in C65 mode and once on the comparator device. A comparison between the measurements was performed using Deming regression analysis. The results are summarized below.
Method Comparison- $\mathrm{cCl}^{-}$ in arterial and venous whole blood
| Parameter | Sample type | Mode | n | Min-max | Intercept | Slope | R2 | MDLs (mmol/L) | Bias at MDLs |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| cCl- | A | S65 | 222 | 88-148.1 | -0.26 | 1.00 | 1.00 | 98 | -0.374 |
| | | | | | | | | 107 | -0.385 |
| | | SP65 | 215 | 89.2-148.2 | 0.02 | 1.00 | 1.00 | 98 | -0.334 |
| | | | | | | | | 107 | -0.366 |
| | V | S65 | 231 | 86.2-148.1 | -0.22 | 1.00 | 1.00 | 98 | -0.339 |
| | | | | | | | | 107 | -0.350 |
| | | SP65 | 221 | 86.5-148.2 | -0.09 | 1.00 | 1.00 | 98 | -0.319 |
| | | | | | | | | 107 | -0.340 |
Method Comparison- $\mathrm{cCa^{2 + }}$ $\mathrm{cNa^{+}}$ , and $\mathrm{cCl^{-}}$ in capillary whole blood
| Parameter | Blood type of Comparator | N | Contrived (%) | Min-max | Slope | Intercept | R2 | MDLs (mmol/L) | Bias at MDLs |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| cNa+ (mmol/L) | Arterial | 116 | 9.5 | 117-179 | 1.02 | -0.542 | 0.93 | 136 | 2.05 |
| | | | | | | | | 146 | 2.24 |
| | Venous | 116 | 9.5 | 117-179 | 1.02 | -0.964 | 0.93 | 136 | 1.85 |
| | | | | | | | | 146 | 2.06 |
| cCa2+ (mg/dL) | Arterial | 111 | 8.1 | 2.53-9.78 | 0.94 | 0.442 | 0.97 | 3.41 | 0.24 |
| | | | | | | | | 4.60 | 0.17 |
| | | | | | | | | 5.17 | 0.14 |
| | | | | | | | | 5.81 | 0.1 |
| | Venous | 111 | 8.1 | 2.53-9.78 | 0.95 | 0.338 | 0.96 | 3.41 | 0.17 |
| | | | | | | | | 4.60 | 0.11 |
| | | | | | | | | 5.17 | 0.08 |
| | | | | | | | | 5.81 | 0.05 |
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| Parameter | Blood type of Comparator | N | Contrived (%) | Min-max | Slope | Intercept | R2 | MDLs (mmol/L) | Bias at MDLs |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| cCl^{-} (mmol/L) | Arterial | 115 | 8.7 | 88.4-148.7 | 1.02 | -1.512 | 0.96 | 98 | 0.54 |
| | | | | | | | | 107 | 0.73 |
| | Venous | 116 | 8.7 | 88.4-148.7 | 1 | 2.753 | 0.96 | 98 | 2.39 |
| | | | | | | | | 107 | 2.35 |
2. **Matrix Comparison:**
Not applicable.
C **Clinical Studies:**
1. **Clinical Sensitivity:**
Not applicable.
2. **Clinical Specificity:**
Not applicable.
3. **Clinical Cut-Off:**
Not applicable.
4. **Other Clinical Supportive Data (When 1. and 2. Are Not Applicable):**
Not applicable.
D **Expected Values/Reference Range:**
The reference range for cCl$^-$ cited from literature, for a normal, healthy population is 98-107 mmol/L$^1$. Refer to K241037 for reference range information for cNa$^+$ and cCa$^{2+}$.
$^{1}$Burtis CA, Ashwood ER, Bruns DE. Tietz textbook of clinical chemistry and molecular diagnostics. 5th ed. St. Louis: Saunders Elsevier, 2012.
VIII **Proposed Labeling:**
The labeling supports the finding of substantial equivalence for this device.
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IX Conclusion:
The submitted information in this premarket notification is complete and supports a substantial equivalence decision.
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