Multicenter evaluation of a new immunoassay for procalcitonin measurement on the Kryptor System

We compared the manually performed LUMItest procalcitonin (PCT) assay with the newly developed fully mechanized Kryptor PCT assay and determined the essential assay characteristics of this assay. The new Kryptor PCT assay was evaluated according to modified NCCLS EP-10/EP-6 protocols in five different laboratories. Samples from 696 patients were assayed using the original LUMItest PCT assay and the new Kryptor PCT assay. Possible interference by hemoglobin, triglycerides and bilirubin was evaluated by spiking patient plasma with the appropriate substances. The functional assay sensitivity (FAS) was determined by analyzing samples with low PCT concentrations. The FAS of the new Kryptor PCT assay was 0.04 ng/ml and the imprecision within- and between-series below 5% and below 10%, respectively. Within the smallest range of determination, from 0.3 ng/ml to 50 ng/ml, common to the LUMItest PCT assay (x) and the Kryptor PCT assay (y) the values correlated well: y=0.64+0.94x, s.xy=2.78 ng/ml. The performance characteristics of the Kryptor PCT assay are fully compatible with the intended clinical use. The assay allows determination of PCT in a turnaround time (TAT) of about 20 minutes and thus is adequate for STAT analyses.