PCT LIA > Assay Characteristics
Measuring Range
Precision
Linearity of Precision
Functional Sensitivity
Specificity
"High Dose Hook" Effect
Interferences to Sequence Analogous Substances
Influence of Medicaments
Measuring Range
The BRAHMS PCT LIA assay measures concentrations between 0.3 and 500 ng/ml.
Precision
determined with patient sera from clinical routine
BRAHMS PCT LIA shows a
high precision in the determination of serum/plasma
PCT concentrations. The intra-assay CV and the inter-assay
CV are 6-10% in the clinically relevant PCT concentration
range.
Linearity
of Precision |
|
Sample |
Dilution |
Observed
Value
[ng/ml]
|
Expected
Value
[ng/ml] |
Recovery
(%) |
| 1 |
undiluted |
30.9
|
|
|
| 1:2 |
15.1 |
30.2 |
107 |
| 1:4 |
7.08 |
28.3 |
100 |
| 1:8 |
3.5 |
28.0 |
99 |
| 1:16 |
1.63 |
26.1 |
93 |
| |
|
28.2 |
|
| 2 |
undiluted |
333.0 |
|
|
| 1:2 |
166.0 |
332.0 |
96 |
| 1:4 |
85.5 |
342.0 |
99 |
| 1:8 |
43.6 |
348.8 |
101 |
| 1:16
|
22.2 |
355.2 |
103 |
| |
|
344.5 |
|
| 3 |
undiluted |
482.0 |
|
|
| 1:2 |
247.0 |
494.0 |
98 |
| 1:4 |
125.0 |
500.0 |
100 |
| 1:8 |
62.2 |
497.6 |
99 |
| 1:16 |
32.2 |
515.2 |
103 |
| |
|
501.7 |
|
| 4 |
undiluted |
6.14 |
|
|
| 1:2 |
3.01 |
6.0 |
102 |
| 1:4 |
1.59 |
6.4 |
108 |
| 1:8 |
0.72 |
5.8 |
98 |
| 1:16 |
0.35 |
5.5 |
93 |
| |
|
5.9 |
|
Functional
Sensitivity
The functional sensitivity
(defined as the lowest analyte concentration that can
be determined with an inter-assay CV <20) has been
assessed as being 0.3 ng/ml with a probability of 95%.
Specificity
The antibodies used in
this assay show no cross-reaction with human calcitonin
(up to 2.5 ng/ml), human katacalcin (up to 10 ng/ml),
human a-CGRP and b-CGRP (up to 4 µg/ml).
"High
Dose Hook" Effect
The "high-dose hook"
effect is observed only at PCT concentrations higher
900 ng/ml. Please see instruction
manual for further details.
Interferences
to Sequence Analogous Substances |
| Substances
|
Non-interfering
Concentrations |
| Calcitonin
(human) |
<=
10 ng/ml |
| Katacalcin
(human) |
<=
10 ng/ml |
| a-human
CGRP* |
<=
10 000 ng/ml |
| b-human
CGRP* |
<=
10 000 ng/ml |
Influence
of Medicaments
An influence of antimicrobial
chemotherapeutics, vaso-active drugs, analgetics,
anticoagulants or diuretics on the PCT-measurement
has not been observed. Drugs which lead to a massive
release of cytokines may lead to an increase of
the PCT level. |
|
|
Medicament |
Cross
Reactivity (%) |
Antimicrobial
Chemotherapeutics |
Imipinen
(Zienam®, MSD)* |
<
1 x 10-4 |
| Cefotaxim (Claforan®,
Hoechst)* |
< 4 x 10-4 |
| Vancomycin (Vancomycin,
Lederle) |
< 1 x 10-4
|
| Vaso-Active
Drugs |
Dopamin
(Dopamin, Fresenius) |
<
1 x 10-4 |
| Noradrenalin
(Arterenol®, Hoechst)* |
< 2 x 10-4 |
| Dobutamin (Dobutamin
Hexal) |
< 5 x 10-3
|
| Other |
Fentanyl
(Fentanyl, Janssen) |
<
1 x 10-2 |
| Heparin |
< 100 IU/ml
without effect |
| Furosemid (Lasix®,
Hoechst)* |
< 1 x 10-4
|
* Zienam®
is a registered trademark of MSD. Claforan®, Arterenol®
and Lasix® are registered trademarks of Hoechst.
