Human Troponin-I
116
SUMMARY AND EXPLANATION OF THE TEST
Cardiac Troponin-I (cTnI) is a 23.8 kD regulatory subunit of the troponin complex that is associated with the actin thin filament within cardiac muscle cells. The
troponin complex is composed of troponin-C and troponin-T, and it plays an integral role in the regulation of cardiac muscle contraction. Extensive clinical studies
have demonstrated that cTnI is slowly released into the blood within hours of myocardial infarction (MI) or ischemic damage. cTnI elevation is detectable in serum
within 4-6 hours after the onset of chest pain, and can remain elevated for up to 10 days following MI. cTnI measurements are highly specific for myocardial
damage, and can be useful for identifying cardiac injury from different sources, including surgery, trauma, and intensive exercise. Clinical studies have also shown
the patients with acute coronary syndromes (ACS) were at greater risk of progressing to MI if cTnI is elevated relative to an upper reference limit for healthy
individuals. This has spurred increasing attention in recent years on high sensitivity cTnI measurement. Potential benefits include more rapid diagnosis in ACS,
population screening, prognostic information in stable patients, and clinical drug development.
AEB
%CVdose
Troponin-I, pg/mL
Healthy donors
Troponin-I, pg/mL
Troponin-I, pg/mL
Figure 2: Simoa Troponin-I CV profile. Diluted serum
Figure 1: SimoaTM Troponin-I immunoassay
calibration curve. Four-parameter curve fit
parameters are depicted.
samples were assayed in reps of 3 over multiple days
and instruments (16 runs, 144 determinations). 95%
confidence intervals (CI) are depicted.
Median [TnI]
0.646 pg/mL
Median [TnI]
0.647 pg/mL
EDTA plasma
Serum
Figure 3: [Troponin-I] in EDTA plasma (n = 28)
and serum (n = 38). Error bars depict mean and
SEM. Troponin-I was measurable in all samples
tested.
Table 1: General characteristics of Simoa Human Troponin-I immunoassay
Calibration range
0-300 pg/mL
Dynamic range1
0-1200 pg/mL
Lower limit of detection (2.5 SD from zero, n = 3 reps x 26 runs across 2 instmts and 10 days, mean LoD2)
0.010 pg/mL
Lower limit of quantification (≤20% CVdose at 95% CI see Figure 2)
0.079 pg/mL
Spike-recovery (cTnI spiked into 24 serum samples at 0.5, 5, and 50 pg/mL , mean3)
80.5%
Linearity (high cTnI serum sample admixed with low TnI sample, mean of 10 levels)
85.9%
Dilution linearity (2 to 16-fold serial dilution of serum with Sample Diluent, mean of 3 exps4)
89.5%
Endogenous interferences (bilirubin, hemoglobin, protein, triglycerides,5 mean of 6 samples)
<20%
Sample volume
42 µL
Total time to first result
45 min
1Samples
auto-diluted 4X.
2SD
0.0053 pg/mL.
3Range
64.1 -103.7%.
4Range
of means at each dilution: 82.0-100.67%.
520
The Simoa Human
Troponin-I immunoassay
reliably quantifies
Troponin-I in serum and
plasma in healthy subjects,
with median Troponin-I
values well above the
sensitivity limits.
mg/dL, 500 mg/dL, 12 g/dL, and 1000 mg/dL respectively.
Table 2: Precision characteristics of Simoa Human Troponin-I immunoassay.
Precision was determined with guidance
from CLSI Protocol EP5-A. Five samples consisting of two serum-based panels, one plasma-based panel, and two troponin-I
controls were assayed in replicates of three at two separate times per day for five days using a single stored calibration curve and
a single lot of reagents. Analysis of variance (fully nested ANOVA) results are summarized in the following table.
Sample
Mean
Troponin-I
(pg/mL)
Control 1
Control 2
Panel 1
Panel 2
Panel 3
Assay designed by Purvish
2.55
115
2.04
5.73
54.4
Within Run
Between Run
Between Day
%CV (n=30)
%CV (n=10)
%CV (n=5)
7.6
5.4
9.7
5.9
4.8
5.1
8.1
3.0
0.0
3.8
7.2
9.7
0.0
1.0
1.8
Simoa
HD-1 Analyzer
For Research Use Only. Not for use in diagnostic procedures.
USER-116-02 08JAN2015