Xn20 analyzer

Hemoglobin, ferritin, and CRP concentrations were determined by Medlab Central Medical Testing Laboratory (Palmerston North, New Zealand) using standard procedures. Hemoglobin concentration was determined in EDTA-treated blood using the sodium lauryl sulfate method on an automated Sysmex XN20 analyzer. Ferritin concentration was determined in serum samples using an electrochemiluminescence immunoassay (Elecsys^® Ferritin, Roche Diagnostics International Ltd) on a Roche Cobas e602 analyzer. CRP concentration was determined in serum samples using the immunoturbidometric method (Roche Diagnostics International Ltd) on a Cobas C analyzer.

All test samples (including PCT and blood culture) were collected within the first 12 h after the development of fever in patients. The “criterion of fever” was a body temperature ≥ 38.0°C [9 (link)]. Blood samples were cultured using an American BD FX400 automatic blood culture system (Becton, Dickinson and Company, USA). Blood culture results were defined as negative (no infection) if there was no microbial growth after five days. The PCT levels were measured using a Roche E411 autoimmune analyzer (Roche Diagnostics, Germany), and D-dimer levels were analyzed using an ACL TOP700 analyzer (Werfen Inc., Spain); the serum biochemical indices were measured using an AU5832 automatic biochemical analyzer (Beckman Coulter Inc.). The blood routine index was analyzed using an XN-20 analyzer (SYSMEX, Japan).