When compared against their respective threshold values of 0.1 ng/mL or 0.5 ng/mL (procalcitonin) and 10 mg/L or 20 mg/L (CRP), elevated procalcitonin predicted the presence of bacterial infection with a sensitivity of 90 % (87–92 %) and a specificity of 39 % (35–43 %) using the lower threshold of 0.1 ng/mL, or a sensitivity of 60 % (56–65 %) and specificity of 76 % (72–79 %) for the higher threshold of 0.5 ng/ml. This evidence concerns the gene CRP and bacterial infectious disease.