Abbott i-STAT 1 System Manual page 434

*The i-STAT System can be configured with the preferred units.
To convert a result from mmol/L to mg/dL, multiply the mmol/L value by 4. To convert mmol/L to mEq/L
multiply the mmol/L value by 2.
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
Although most of the calcium in blood is bound to protein or complexed to smaller anionic species, the
biologically active fraction of calcium is free ionized calcium. Through its role in a number of enzymatic
reactions and in membrane transport mechanisms, ionized calcium is vitally important in blood coagulation,
nerve conduction, neuromuscular transmission and in muscle contraction. Increased ionized calcium
(hypercalcemia) may result in coma. Other symptoms reflect neuromuscular disturbances, such as
hyperreflexia and/or neurologic abnormalities such as neurasthenia, depression or psychosis. Decreased
ionized calcium (hypocalcemia) often results in cramps (tetany), reduced cardiac stroke work and depressed
left ventricular function. Prolonged hypocalcemia may result in bone demineralization (osteoporosis) which
can lead to spontaneous fractures. Measurements of ionized calcium have proven of value under the
following clinical conditions: transfusion of citrated blood, liver transplan tation, open heart surgery, neonatal
hypocalcemia, renal disease, hyperparathyroidism, malignancy, hypertension and pancreatitis.
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 guide line EP9-A
collected in lithium heparin Vacutainer
comparative methods within 10 minutes of each other.
Deming regression analysis
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." The correlation coefficient, r, can be used as a guide to assess the adequacy of the comparative method range in overcoming this
4
problem. As a guide, the range of data can be considered adequate for r >0.975.
Precision Data (mmol/L)
Aqueous Control
Level 1
Level 3
iCa - 2
tubes and analyzed in duplicate on the i-STAT System and on the
®
4 was performed on the first replicate of each sample. In the method comparison
Mean SD
1.60 0.017
0.84 0.012
Art: 714179-01P
. Venous blood samples were
3
%CV
1.1
1.4
Rev. Date: 15-Jul-16