Piccolo Electrolyte Reagent Disc

Piccolo Electrolyte Reagent Disc
Piccolo® Electrolyte Reagent Disc
Customer and Technical Service: 800-822-2947
CLIA Waived: Use lithium heparin whole blood, only
Moderate Complexity: Use lithium heparin whole blood
lithium heparin plasma, or serum
November 2007
PN: 400-7116 Rev. H
© 2001, Abaxis, Inc., Union City, CA 94587
1. Intended Use
The Piccolo® Electrolyte Reagent Disc, used with the Piccolo Blood Chemistry Analyzer or the Piccolo xpress™ Chemistry
Analyzer, is intended to be used for the in vitro quantitative determination of chloride, potassium, sodium, and total carbon
dioxide in heparinized whole blood, heparinized plasma, or serum.
The tests on this panel are waived under CLIA ’88 regulations. If a laboratory modifies the test system instructions, then the
tests are considered high complexity and subject to all CLIA requirements. For CLIA waived labs, only lithium heparin whole
blood may be tested. For use in moderate complexity labs, lithium heparinized whole blood, lithium heparinized plasma, or
serum may be used.
A CLIA Certificate of Waiver is needed to perform CLIA waived testing. A Certificate of Waiver can be obtained from the
Centers for Medicare & Medicaid Services (CMS). Please contact the Commission on Laboratory Accreditation (COLA) at 1800-981-9883 for assistance in obtaining one.
2. Summary and Explanation of Tests
The Piccolo Electrolyte Reagent Disc and the Piccolo Blood Chemistry Analyzer comprise an in vitro diagnostic system that
aids the physician in diagnosing the following disorders:
Chloride:
Potassium:
Sodium:
Total carbon dioxide:
Dehydration, prolonged diarrhea and vomiting, renal tubular
disease, hyperparathyroidism, burns, salt-losing renal diseases,
overhydration and thiazide therapy.
Renal glomerular or tubular disease, adrenocortical insufficiency,
diabetic ketacidosis, excessive intravenous potassium therapy,
sepsis, panhypopituitarism, in vitro hemolysis,
hyperaldosteronism, malnutrition, hyperinsulinism, metabolic
alkalosis and gastrointestinal loss.
Dehydration, diabetes insipidus, loss of hypotonic
gastrointestinal fluids, salt poisoning, selective depression of
sense of thirst, skin losses, burns, sweating, hyperaldosteronism,
CNS disorders, dilutional, depletional and delusional
hyponatremia and syndrome of inappropriate ADH secretion.
Primary metabolic alkalosis and acidosis and primary respiratory
alkalosis and acidosis.
As with any diagnostic test procedure, all other test procedures including the clinical status of the patient, should be
considered prior to final diagnosis.
3. Principle of Procedure
Chloride (CL-)
The method is based on the determination of chloride-dependent activation of α-amylase activity. Deactivated α-amylase
is reactivated by addition of the chloride ion, allowing the calcium to re-associate with the enzyme. The reactivation of
α-amylase activity is proportional to the concentration of chloride ions in the sample. The reactivated α-amylase converts
the substrate, 2-chloro-p-nitrophenyl-α-D-maltotrioside (CNPG3) to 2-chloro-p-nitrophenol (CNP) producing color and
α-maltotriose (G3). The reaction is measured bichromatically and the increase in absorbance is directly proportional to the
reactivated α-amylase activity and the concentration of chloride ion in the sample.1
Page 1 of 60
α-Amylase
CNPG3
CNP + G3
Cl-, Ca2+
Potassium (K+)
Spectrophotometric methods have been developed that allow the measurement of potassium concentration on standard clinical
chemistry instrumentation. The Abaxis enzymatic method is based on the activation of pyruvate kinase with potassium and
shows excellent linearity and negligible susceptibility to endogenous substances.2,3,4 Interference from sodium and ammonium
ion are minimized with the addition of Kryptofix and glutamine synthetase, respectively.2
In the coupled-enzyme reaction, pyruvate kinase (PK) dephosphorylates phosphoenolpyruvate (PEP) to form pyruvate. Lactate
dehydrogenase (LDH) catalyzes conversion of pyruvate to lactate. Concomitantly, NADH is oxidized to NAD+.
K+ , PK
ADP + PEP
Pyruvate + ATP
Pyruvate + NADH + H+
LDH
Lactate + NAD+
The rate of change in absorbance difference between 340 nm and 405 nm is due to the conversion of NADH to NAD+ and is
directly proportional to the amount of potassium in the sample.
Sodium (NA+)
Colorimetric and enzymatic methods have been developed that allow the measurement of sodium concentration on standard
clinical chemistry instrumentation.5,6,7 In the Abaxis enzymatic reaction, β-galactosidase is activated by the sodium in the
sample. The activated enzyme catalyzes the reaction of ο-nitrophenyl-β-D-galactopyranoside (ONPG) to ο-nitrophenol and
galactose.
Na+
ONPG
β-Galactosidase
ο-Nitrophenol + Galactose
Total Carbon Dioxide (tCO2)
Total carbon dioxide in serum or plasma exists as dissolved carbon dioxide, carbamino derivatives of proteins, bicarbonate
and carbonate ions and carbonic acid. Total carbon dioxide can be measured by pH indicator, CO2 electrode and
spectrophotometric enzymatic methods, which all produce accurate and precise results.8,9 The enzymatic method is well suited
for use on a routine blood chemistry analyzer without adding complexity.
In the enzymatic method, the specimen is first made alkaline to convert all forms of carbon dioxide (CO2) toward bicarbonate
(HCO3-) Phosphoenolpyruvate (PEP) and HCO3- then react to form oxaloacetate and phosphate in the presence of
phosphoenolpyruvate carboxylase (PEPC). Malate dehydrogenase (MDH) catalyzes the reaction of oxaloacetate and reduced
nicotinamide adenine dinucleotide (NADH) to NAD+ and malate. The rate of change in absorbance due to the conversion of
NADH to NAD+ is directly proportional to the amount of tCO2 in the sample.
PEP + HCO3-
PEPC
Oxaloacetate + NADH + H+
Oxaloacetate + Phosphate
MDH
Page 2 of 60
NAD+ + Malate
4. Principle of Operation
See the Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s Manual, for the Principles and
Limitations of the Procedure.
5. Description of Reagents
Reagents
Each Piccolo Electrolyte Reagent Disc contains dry test-specific reagent beads (described below). A dry sample blank reagent
(comprised of buffer, surfactants, excipients, and preservatives) is included in each disc for use in calculating concentrations of
chloride (CL-), potassium (K+), sodium (NA+), and total carbon dioxide (tCO2). Each disc also contains a diluent consisting of
surfactants and preservatives.
Table 1: Reagents
Component
Quantity/Disc
Adenosine-5’-diphosphate
Amylase
Calcium acetate
2-Chloro-4-nitrophenyl – alpha-maltotrioside (CNPG3)
Citric acid, trisodium salt
Ethylenediaminetetraacetic acid (EDTA)
Ethylene glycol-bis(β-aminoethyl ether)-N,N,N’,N’-tetraacetic acid (EGTA)
β-Galactosidase
4,7,13,16,21,24-Hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane (Kryptofix 222)
Lactate dehydrogenase
Magnesium acetate
Malate dehydrogenase (porcine heart)
N-acetyl cysteine
ß-Nicotinamide adenine dinucleotide, reduced (NADH)
α-Oxoglutarate
4,7,13,16,21-Pentaoxa-1,10-diazabicyclo[8.8.5]tricosane (Kryptofix 221)
Phosphoenol pyruvate
Phosphoenol pyruvate carboxylase
Pyruvate kinase
Buffers, surfactants, excipients and preservatives
13.9µg
0.036U
25.2µg
52.5µg
567µg
182µg
3.7µg
0.0046U
0.3µg
0.3U
15µg
0.1U
15.3µg
21µg
7.9µg
84µg
34µg
0.001U
0.01U
Warnings and Precautions
•
For In vitro Diagnostic Use
•
The diluent container in the reagent disc is automatically opened when the analyzer drawer closes. A disc with an opened
diluent container can not be re-used. Ensure that the sample or control has been placed into the disc before closing the
drawer.
•
Used reagent discs contain human body fluids. Follow good laboratory safety practices when handling and disposing of
used discs.10 See the Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s Manual for
instructions on cleaning biohazardous spills.
•
The reagent discs are plastic and may crack or chip if dropped. Never use a dropped disc as it may spray biohazardous
material throughout the interior of the analyzer.
•
Reagent beads may contain acids or caustic substances. The operator does not come into contact with the reagent beads
when following the recommended procedures. In the event that the beads are handled (e.g., cleaning up after dropping and
cracking a reagent disc), avoid ingestion, skin contact, or inhalation of the reagent beads.
Page 3 of 60
Instructions for Reagent Handling
Reagent discs may be used directly from the refrigerator without warming. Do not allow discs sealed in their foil pouches to
remain at room temperature longer than 48 hours prior to use. Open the sealed foil pouch, remove the disc and use according to
the instructions provided in the Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s
Manual. A disc not used within 20 minutes of opening the pouch should be discarded.
Storage
Store reagent discs in their sealed pouches at 2-8°C (36-46°F). Do not expose opened or unopened discs to direct sunlight or
temperatures above 32°C (90°F). Reagent discs may be used until the expiration date included on the package. The expiration
date is also encoded in the bar code printed on the bar code ring. An error message will appear on the Piccolo Blood Chemistry
Analyzer or the Piccolo xpress Chemistry Analyzer Display if the reagents have expired.
Indications of Reagent Disc Instability/Deterioration
A torn or otherwise damaged pouch may allow moisture to reach the unused disc and adversely affect reagent performance.
Do not use a disc from a damaged pouch.
6. Instrument
See the Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s Manual for complete
information on use of the analyzer.
7. Sample Collection and Preparation
Sample collection techniques are described in the “Sample Collection” section of the Piccolo Blood Chemistry Analyzer or the
Piccolo xpress Chemistry Analyzer Operator’s Manual.
•
The minimum required sample size is ~100 µL of heparinized whole blood, heparinized plasma, serum or control material.
The reagent disc sample chamber can contain up to 120 µL of sample.
•
Whole blood samples obtained by venipuncture must be homogeneous before transferring a sample to the reagent disc.
Gently invert the collection tube several times just prior to sample transfer. Do not shake the collection tube; shaking may
cause hemolysis.
•
Hemolysis may cause erroneously high results in potassium assays. This problem may go undetected when analyzing
whole blood (release of potassium from as few as 0.5% of the erythrocytes can increase the potassium serum level by 0.5
mmol/L). In addition, even unhemolyzed specimens that are not promptly processed may have increased potassium levels
due to intracellular potassium leakage.11
•
Whole blood venipuncture samples should be run within 60 minutes of collection.12 The sample may be separated into
plasma or serum and stored in capped sample tubes at 2-8°C (36-46°F), if the sample cannot be run within 60 minutes.
•
Use only lithium heparin (green stopper) evacuated specimen collection tubes for whole blood or plasma samples. Use
no-additive (red stopper) evacuated specimen collection tubes or serum separator tubes (red or red/black stopper) for
serum samples.
•
Start the test within 10 minutes of transferring the sample into the reagent disc.
•
The concentration of total carbon dioxide is most accurately determined when the assay is done immediately after opening
the tube and as promptly as possible after collection and processing of the blood in the unopened tube. Ambient air
contains far less carbon dioxide than does plasma, and gaseous dissolved carbon dioxide will escape from the specimen
into the air, with a consequent decrease in carbon dioxide value of up to 6 mmol/L in the course of 1 hour.13
8. Procedure
Materials Provided
•
One Piccolo Electrolyte Reagent Disc PN: 400-1022 (a box of discs PN: 400-0022)
Page 4 of 60
Materials Required but not Provided
•
•
•
•
Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer
Sample transfer pipettes (fixed volume approximately 100 µL) and tips are provided with each Piccolo Blood Chemistry
Analyzer or the Piccolo xpress Chemistry Analyzer and may be reordered from Abaxis.
Commercially available control reagents recommended by Abaxis (contact Abaxis Technical Support for approved control
materials and expected values).
Timer
Test Parameters
The Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer operates at ambient temperatures between
15°C and 32°C (59-90°F). The analysis time for each Piccolo Electrolyte Reagent Disc is less than 14 minutes. The analyzers
maintain the reagent disc at a temperature of 37°C (98.6°F) over the measurement interval.
Test Procedure
The complete sample collection and step-by-step operating procedures are detailed in the Piccolo Blood Chemistry Analyzer or
the Piccolo xpress Chemistry Analyzer Operator’s Manual.
Calibration
The Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer is calibrated by the manufacturer before
shipment. The bar code printed on the bar code ring provides the analyzer with disc-specific calibration data. See the Piccolo
Chemistry Analyzer Operator’s Manual.
Quality Control
See Section 2.4 of the Piccolo Operator’s Manual or Section 6 (Calibration and Quality Control) of the Piccolo xpress
Operator’s Manual. Performance of the Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer can be
verified by running controls. For a list of approved quality control materials with acceptance ranges, please contact Abaxis
Technical Support. Other human serum or plasma-based controls may not be compatible. Quality control materials should be
stored as per the package-insert included with the controls.
If control results are out of range, repeat one time. If still out of range, call Technical Support. Do not report results if controls
are outside their labeled limits. See the Piccolo or Piccolo xpress Operator’s Manual for a detailed discussion on running,
recording, interpreting, and plotting control results.
Waived Laboratories: Abaxis recommends control testing as follows:
•
•
•
•
at least every 30 days
whenever the laboratory conditions have changed significantly, e.g. Piccolo moved to a new location or
changes in temperature control
when training or retraining of personnel is indicated
with each new lot (CLIA waived tests in waived status labs)
Non-Waived Laboratories: Abaxis recommends control testing to follow federal, state, and local guidelines.
9. Results
The Piccolo Blood Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer automatically calculates and prints the
analyte concentrations in the sample. Details of the endpoint and rate reaction calculations are found in the Piccolo Blood
Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s Manual.
Interpretation of results is detailed in the Operator’s Manual. Results are printed onto result cards supplied by Abaxis. The
result cards have an adhesive backing for easy placement in the patient’s files.
10. Limitations of Procedure
General procedural limitations are discussed in the Piccolo Blood Chemistry Analyzer Operator’s Manual or the Piccolo xpress
Chemistry Analyzer.
Page 5 of 60
•
The only anticoagulant recommended for use with the Piccolo Blood Chemistry System or the Piccolo xpress Chemistry
Analyzer is lithium heparin. Abaxis has performed studies demonstrating that EDTA, fluoride, oxalate, and any
anticoagulant containing ammonium ions will interfere with at least one chemistry contained in the Piccolo Electrolyte
Reagent Disc. Do not use sodium heparin.
•
Samples with hematocrits in excess of 62-65% packed red cell volume (a volume fraction of 0.62-0.65) may give
inaccurate results. Samples with high hematocrits may be reported as hemolyzed. These samples may be spun down to get
plasma then re-run in a new reagent disc.
•
Any result for a particular test that exceeds the assay range should be analyzed by another approved test method or
sent to a referral laboratory. Do not dilute the sample and run it again on the Piccolo Blood Chemistry Analyzer or
the Piccolo xpress Chemistry Analyzer.
Warning:
Extensive testing of the Piccolo Blood Chemistry System or the Piccolo xpress Chemistry Analyzer has
shown that, in very rare instances, sample dispensed into the reagent disc may not flow smoothly into the
sample chamber. Due to the uneven flow, an inadequate quantity of sample may be analyzed and several
results may fall outside the reference ranges. The sample may be re-run using a new reagent disc.
Interference
Substances were tested as interferents with the analytes. Human serum pools were prepared. The concentration at which each
potential interferent was tested was based on the testing levels in NCCLS EP7-P.14
Effects of Endogenous Substances
• Physiological interferents (hemolysis, icterus and lipemia) cause changes in the reported concentrations of some analytes.
The sample indices are printed on the bottom of each result card to inform the operator about the levels of interferents
present in each sample.
•
The Piccolo Blood Chemistry System or the Piccolo xpress Chemistry Analyzer suppresses any results that are affected by
>10% interference from hemolysis, lipemia or icterus. “HEM”, “LIP”, or “ICT” respectively, is printed on the result card
in place of the result.
•
Extremely elevated amylase levels (>9,000 U/L) will have a significant effect, >10% increase, on the chloride result. The
concentration of amylase is not evaluated by the Piccolo system for each specimen.
•
The potassium assay in the Piccolo system is a coupled pyruvate kinase (PK) / lactate dehydrogenase (LDH) assay.
Therefore, in cases of extreme muscle trauma or highly elevated levels of creatine kinase (CK), the Piccolo may recover a
falsely elevated potassium (K+) value. In such cases, unexpected high potassium recoveries need to be confirmed utilizing
a different methodology.
•
For maximum levels of endogenous substances contact Abaxis Technical Support.
Effects of Exogenous and Therapeutic Substances
•
Thirty-five exogenous and therapeutic substances were selected as potential interferents for Abaxis test methods based on
recommendations by Young.15 Significant interference is defined as greater than ± 10% shift in the result for a normal
range specimen. Human serum pools were supplemented with known concentrations of the drugs or chemicals and then
analyzed. Please see Table 2 for a list of exogenous and therapeutic substances evaluated. Please see TABLE 3 for a list
of analytes where interference was observed.
Page 6 of 60
Table 2: Exogenous and Therapeutic Substances Evaluated
Potential Interferent
Highest Concentration Tested
(mg/dL unless otherwise specified)
Acetaminophen
Acetoacetate
Acetylsalicylic Acid
Ampicillin
Ascorbic acid
Caffeine
Cephalothin (Keflin)
Chloramphenicol
Cimetidine
Dopamine
Epinephrine
Erythromycin
Glutathione
Hydrochlorothiazide
Ibuprofen
Isoniazide
Ketoprofen
L-dopa
Lidocaine
Lithium Lactate
Methicillin
Methotrexate
Metronidazole
Nafcillin
Nitrofurantoin
Oxacillin
Oxaloacetate
Penicillin G
Phenytoin (5,5-Diphenylhydantion)
Proline
Rifampin
Salicylic Acid
Sulfadiazine
Sulfanilamide
Theophylline
Page 7 of 60
100
102
50
30
3
10
400
100
16
13
1
10
30
7.5
50
4
50
5
1
84
100
0.5
5
1
20
1
132
100
3
4
0.5
50
150
50
20
Please see Table 3 for a list of analytes where interference was observed.
Table 3: The following substances showed greater than + 10 % shift in the result for a normal range specimen.
Concentration Which
Produces > 10%
Interference
Potassium
Penicillin G
Sulfadiazine
100
150
17% inc.
12% dec.
Sodium
Cephalothin
Methotrexate
Penicillin G
400
0.5
100
12% inc.
11% inc.
10% inc.
Total Carbon Dioxide
Acetaminophen
Ascorbic Acid
Cephalothin
Cimetidine
Erythromycin
Lidocaine
Methotrexate
Nitrofurantoin
Salicylic Acid
Sulfadiazine
100
20
400
16
10
1
0.5
20
50
150
11% inc.
12% dec.
13% inc.
19% dec.
21% dec.
23% inc.
80% dec.
13% inc.
17% dec.
25% dec.
A
•
% InterferenceA
Observed
Dec. = decreased concentration of the specified analyte; Inc. = increased concentration of the specified analyte
For the Chloride assay, bromide at toxic levels (≥ 15 mmol/L) can cause a significant effect (> 10% increase), on the
chloride result. Iodide at very high concentrations (30 mmol/L, highest level tested) has no effect. Normal
physiological levels of bromide and iodide do not interfere with the Piccolo Chloride Test System.
11. Expected Values
Samples from approximately 140 adult males and females were analyzed on the Piccolo Blood Chemistry Analyzer to
determine the reference interval. These ranges were calculated based on the 95% reference interval estimated from the
combined (overall) values obtained from the reference subjects.16 It is recommended that your office or institution establish
normal ranges for your particular patient population.
Table 4: Piccolo Reference Intervals
Analyte
Chloride (CL-)
Potassium (K+)
Sodium (NA+)
Total Carbon Dioxide (tCO2)
Common Units
98-108 mmol/L
3.6-5.1 mmol/L
128-145 mmol/L
18-33 mmol/L
SI Units
98-108 mmol/L
3.6-5.1 mmol/L
128-145 mmol/L
18-33 mmol/L
12. Performance Characteristics
Linearity
The chemistry for each analyte is linear over the dynamic range listed below when the Piccolo Blood Chemistry Analyzer or
the Piccolo xpress Chemistry Analyzer is operated according to the recommended procedure (refer to the Piccolo Blood
Chemistry Analyzer or the Piccolo xpress Chemistry Analyzer Operator’s Manual).
Page 8 of 60
Table 5: Piccolo Dynamic Ranges
Analyte
Chloride (CL-)
Potassium (K+)
Sodium (NA+)
Total Carbon Dioxide (tCO2)
Common Units
80-135 mmol/L
1.5-8.5 mmol/L
110-170 mmol/L
5-40 mmol/L
SI Units
80-135 mmol/L
1.5-8.5 mmol/L
110-170 mmol/L
5-40 mmol/L
If the analyte concentration is above the measuring range (dynamic range), but less than the system range, the print card will
indicate a “>” sign at the upper limit and an asterisk after the number, e.g. CL- >135* mmol/L. If lower than the dynamic
range, a “<” will be printed with an asterisk, e.g. CL- <80* U/L. For values that are grossly beyond the measurement range
(system range), “~~~” will be printed instead of a result. Any time “~~~” appears on a print card, collect a new sample and
rerun the test. If results for the second sample are suppressed again, please call Abaxis Technical Support.
Sensitivity (Limits of Detection)
The lower limit of the reportable (dynamic) range for each analyte is: chloride 80 mmol/L; potassium 1.5 mmol/L; sodium 110
mmol/L; and total carbon dioxide 5 mmol/L.
Precision
Precision studies were conducted using NCCLS EP5-A guidelines17 with modifications based on NCCLS EP18-P18 for unit-use
devices. Results for within-run and total precision were determined using two levels of commercially available control
materials. The studies made use of multiple instruments and two reagent disc lots. Potassium and total carbon dioxide testing
was performed at two sites over 20 days; sodium testing was performed at one site over 20 days; chloride testing was done at
two sites over a period of five days.
Results of precision studies are shown in Table 6.
Table 6: Precision
Analyte
Chloride (mmol/L)
Control 1
Mean
SD
CV
Control 2
Mean
SD
CV
Potassium (mmol/L)
Control 1
Mean
SD
CV
Control 2
Mean
SD
CV
Sodium (mmol/L)
Control 1
Mean
SD
CV
Control 2
Mean
SD
CV
Sample Size
Within-Run
Total
97.8
1.63
1.7
97.8
1.74
1.7
113.6
1.97
1.7
113.6
2.22
2.0
6.12
0.32
5.2
6.12
0.32
5.7
4.10
0.24
5.9
4.10
0.26
6.3
143.5
2.28
1.6
143.5
2.28
1.6
120.0
2.13
1.8
120.0
2.13
1.8
N = 160
N = 120
N = 80
Page 9 of 60
Table 6: Precision (continued)
Analyte
Sample Size
Total Carbon Dioxide (mmol/L)
Control 1
Mean
SD
CV
Control 2
Mean
SD
CV
Within-Run
Total
21.4
2.29
10.7
21.4
2.29
10.7
10.5
0.90
8.6
10.5
0.90
8.6
N = 120
Correlation
Serum samples were collected and assayed on the Piccolo Blood Chemistry Analyzer and by comparative methods. In some
cases, high and low supplemented samples were used to cover the dynamic range. The samples were chosen to meet the
distribution values in NCCLS EP9-A guideline.19 Representative correlation statistics are shown in Table 7.
Table 7: Correlation of Piccolo Blood Chemistry Analyzer with Comparative Method(s)
Correlation
Coefficient
Slope
Intercept
SEE
N
Sample Range
(mmol/L)
Comparative
Method
Chloride (mmol/L)
0.978
0.982
-1.1
1.84
120
71-118
Vitros 950
Potassium (mmol/L)
0.969
0.863
0.6
0.14
58
2.0-6.8
Radiometer
KNATM 2
Sodium (mmol/L)
0.937
0.782
27.7
3.79
113
116-154
Radiometer
KNATM 2
Total Carbon
Dioxide (mmol/L)
0.947
0.903
2.4
0.84
60
6-39
Cobas Fara
Page 10 of 60
Results of Untrained User Study
An “untrained user” study was conducted in which participants were given only the test instructions and asked to perform
testing of 3 discs with blinded randomized samples. The samples consisted of serum pools prepared at three levels for each of
the four analytes: chloride, potassium, sodium, and total carbon dioxide. The participants were not given any training on the
use of the test. A total of approximately 60 participants were enrolled from 3 sites, representing a diverse demographic
(educational, age, gender, etc) population.
Tables below present the summary of the performance for each analyte.
Chloride (CL-)
N
Mean
%CV
Observed Range
Percent of Results
in the Range
± 2.4%
Level 1
62
94.6
1.8
90 – 100
91.9%
57/62
95%CI: 82.2% to 97.3%
Level 2
62
106.0
1.4
102 – 108
96.8%
60/62
95%CI: 88.8% to 99.6%
Level 3
62
115.5
1.5
110 – 119
95.2%
59/62
95%CI: 86.5% to 99.0%
*
This percent is based on the premise that one cannot distinguish properly between normal and abnormal values when errors
are greater than one-quarter of the normal range. The range of (98 mmol/L - 108 mmol/L) was considered.
Potassium (K+)
N
Mean
%CV
Observed Range
Percent of Results
in the Range
± 8.6%
Level 1
62
3.4
3.3
3.2 – 3.7
100%
62/62
95%CI: 94.2% to 100%
Level 2
62
5.7
2.5
5.2 – 5.9
100%
62/62
95%CI: 94.2% to 100%
Level 3
62
7.2
2.0
6.7 – 7.5
100%
62/62
95%CI: 94.2% to 100%
Level 1
62
122.1
1.0
118 – 127
98.4%
61/62
95%CI: 91.3% to 100%
Level 2
62
140.8
0.8
138 – 143
100%
62/62
95%CI: 94.2% to 100%
Level 3
62
157.5
1.0
154 – 162
100%
62/62
95%CI: 94.2% to 100%
Level 2
62
27.6
4.6
23 – 30
98.4%
61/62
95%CI: 91.3% to 100%
Level 3
62
34.4
3.7
32 – 38
100%
62/62
95%CI: 94.2% to 100%
Sodium (NA+)
N
Mean
%CV
Observed Range
Percent of Results
in the Range
± 3.1%
Total Carbon Dioxide (tCO2)
N
Mean
%CV
Observed Range
Percent of Results
in the Range
± 14.7%
Level 1
62
20.3
5.1
18 –23
100%
62/62
95%CI: 94.2% to 100%
Page 11 of 60
13. Bibliography
1.
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Van Pelt J. Enzymatic determination of sodium, potassium and chloride in serum compared with determination by flame
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Hubl W, et al. Enzymatic determination of sodium, potassium and chloride in abnormal (hemolyzed, icteric, lipemic,
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Helgerson RC, et al. Host-guest Complexation. 50. Potassium and sodium ion-selective chromogenic ionophores. J Amer
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Kumar A, et al. Chromogenic ionophore-based methods for spectrophotometric assay of sodium and potassium in serum
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Skeggs LT Jr. An automatic method for the determination of carbon dioxide in blood plasma. Am J. Clin Pathol
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Scott, M.G. Electrolytes and Blood Gases. In: Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed.
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National Committee for Clinical Laboratory Standards. Interference testing in clinical chemistry; proposed guideline.
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