**Comparison of Procalcitonin Assays on KRYPTOR and LIAISON** ® **XL Analyzers**

#### **Mariella Dipalo \*, Cecilia Gnocchi, Paola Avanzini, Roberta Musa, Martina Di Pietro and Rosalia Aloe**

SSD Biochimica ad Elevata Automazione, Azienda Ospedaliera Universitaria di Parma, Via Gramsci 14, 43126 Parma, Italy

**\*** Correspondence: mdipalo@ao.pr.it

Received: 5 July 2019; Accepted: 6 August 2019; Published: 8 August 2019

**Abstract:** Our laboratory performs procalcitonin (PCT) assays on a Brahms KRYPTOR analyzer with the Brahms PCT sensitive Kryptor kit. In this study, we wanted to compare the assays obtained in this way with the ones performed on the LIAISON ® XL. From January to May 2017, 171 samples were analyzed, of which 65 from female patients (age: 22–98 years) and 106 from male patients (age: 16–97 years). The PCT determination was performed using the LIAISON ® XL and KRYPTOR analyzers, by chemiluminescence (Chemiluminescence immunoassay—CLIA) (LIAISON ® BRAHMS PCT ® II GEN) and immunofluorescence (Brahms PCT sensitive Kryptor) assay, respectively. For the LIAISON ® BRAHMS PCT ® II GEN, 52% of the results were placed between 0.0 and 0.5 ng/mL, 18% between 0.5 and 2.0 ng/mL, and 30% between 2.0 and 100 ng/mL; the mean was 4.09 ng/mL, the median 0.456 ng/mL, the maximum value 97.2 ng/mL, and the minimum value 0.02 ng/mL. For the Brahms PCT sensitive Kryptor, 55% of the results were positioned between 0.0 and 0.5 ng/mL, 21% between 0.5 and 2.0 ng/mL, and 24% between 2.0 and 100 ng/mL; the mean was 3.72 ng/mL, the median 0.39 ng/mL, the maximum value 103 ng/mL, and the minimum value 0.01 ng/mL. The mean of the results obtained with the two methods showed no significant di fferences (3.717 for Kryptor and 4.094 for LIAISON ®). PCT assay with Brahms reagents, both on the Kryptor and LIAISON ®XL platforms, o ffers excellent performance in terms of sensitivity and specificity.

**Keywords:** sepsis; PCT; procalcitonin; immunoassay; antibiotic; chemiluminescence; immunofluorescence
