Abbott i-STAT 1 System Manual page 398

The i-STAT reference range for whole blood listed above is similar to reference ranges derived from
serum or plasma measurements with standard laboratory methods.
The reference range programmed into the analyzer and shown above is intended to be used as a guide
for the interpretation of results. Since reference ranges may vary with demographic factors such as age,
gender and heritage, it is recommended that reference ranges be determined for the population being
tested.
Clinical Significance
Tests for sodium in the blood are important in the diagnosis and treatment of patients suffering from
hypertension, renal failure or impairment, cardiac distress, disorientation, dehydration, nausea and
diarrhea. Some causes of increased values for sodium include dehydration, diabetes insipidus, salt
poisoning, skin losses, hyperaldosteronism and CNS disorders. Some causes for decreased values
for sodium include dilutional hypona tremia (cirrhosis), depletional hyponatremia and syndrome of
inappropriate ADH.
Performance Characteristics
The typical performance data summarized below was collected in health care facilities by health care
professionals trained in the use of the i-STAT System and comparative methods.
Precision data were collected in multiple sites as follows: Duplicates of each control fluid were tested
in the morning and in the afternoon on five days for a total of 20 replicates. The averaged statistics are
presented below.
Method comparison data were collected using CLSI guideline EP9-A
collected in lithium heparin Vacutainer® tubes and analyzed in duplicate on the i-STAT System. A portion
of the specimen was centri fuged and the separated plasma was analyzed in duplicate on comparative
methods within 20 minutes of collection.
Deming regression analysis
comparison table, n is the number of specimens in the data set, Sxx and Syy refer to estimates of
imprecision based on the duplicates of the comparative and the i-STAT methods respectively, Sy.x is the
standard error of the estimate, and r is the correlation coefficient.*
Method comparisons will vary from site to site due to differences in sample handling, comparative
method calibration and other site specific variables.
*The usual warning relating to the use of regression analysis is summarized here as a reminder. For any analyte, "if the data are collected over a
narrow range, the estimate of the regression parameters is relatively imprecise and may be biased. Therefore, predictions made from these estimates
may be invalid." 4 The correlation coefficient, r, can be used as a guide to assess the adequacy of the comparative method range in overcoming this
problem. As a guide, the range of data can be considered adequate for r >0.975.
Precision Data (mmol/L or mEq/L)
Aqueous Control
Level 1
Level 3
Method Comparison (mmol/L or mEq/L)
Beckman
Synchron
n
Sxx
Syy
NA - 2
was performed on the first replicate of each sample. In the method
5
Mean SD
120.0 0.46
160.0 0.53
Kodak
CX 3 Ektachem
®
™
189 142
0.74 0.52
0.53 0.58
Art: 714173-01P
. Venous blood samples were
4
%CV
0.4
0.3
Nova
STAT
700 Profile 5
®
192
0.54
0.53
Rev. Date: 15-Jul-16