PCT sensitive KRYPTOR > Assay Characteristics
Measuring Range
The BRAHMS PCT KRYPTOR assay measures concentrations between 0.02 and 5000 ng/ml (0.02 to 50 ng/ml directly and up to 5000 ng/ml after sample dilution).
Precision
(determined with patient sera from clinical routine)
BRAHMS PCT KRYPTOR shows a high precision in the determination of serum/plasma PCT concentrations. The intra-assay CV and the inter-assay CV are 2-3% on the whole PCT concentration range.
Analytical Sensitivity
The detection limit calculated using the imprecision profile has been assessed as being 0.019 ng/ml with a probability of 95 %.
Functional Assay Sensitivity
The functional assay sensitivity (defined as the lowest analyte concentration that can be determined with an inter-assay CV <20) has been assessed as being 0.06 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 ß-CGRP (up to 4 µg/ml).
Linearity Upon Dilution
The table gives an example of the dilution linearity of a patient serum diluted with diluent. Original concentration: 48.17 ng/ml
| Dilution | Measured value (ng/ml) |
Expecteded value (ng/ml) |
Recovery (%) |
| 1 : 2 | 23.84 | 24.08 | 99.0% |
| 1 : 3 | 16.27 | 16.06 | 101.3% |
| 1 : 5 | 9.59 | 9.63 | 99.6% |
| 1 : 10 | 4.71 | 4.81 | 97.9% |
| 1 : 25 | 1.86 | 1.93 | 96.4% |
Quality Control
Good laboratory practices imply that control samples be used regularly to ensure the quality of the results obtained. These samples must be processed exactly the same way as the assay samples, and it is recommended that their results be analysed using appropriate statistical methods. If selected, KRYPTOR can automatically check the quality of assays at intervals, by statistical analysis on LEVEY JENNINGS graphs.
Standardisation
BRAHMS PCT KRYPTOR has been calibrated against the BRAHMS PCT LIA. Both tests correlate very well. In individual cases, however, there may be deviations (up to 20%) between different test systems. It is, therefore, recommended that always the same test method should be used for follow-up. Correlation to reference assay BRAHMS PCT LIA: PCT concentrations measured with BRAHMS PCT KRYPTOR correlate very well with results obtained with BRAHMS PCT LIA, the standard test for PCT determination (see Fig. 1).
Interfering Substances
Icteric, hemolytic or hyperlipemic samples, or samples which present turbidity or contain fibrin may give inexact results. Such samples are signalled by KRYPTOR®. No interference with test results is seen by concentrations of bilirubin 0.4 mg/ml, haemoglobin < 10 g/l or triglycerides < 10 g/l. 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 ß-CGRP (up to 4 µg/ml).