CALCA and Sepsis: In the 140 HFRS patients without sepsis (72 patients in mild group and 68 patients in severe group), the median serum PCT levels in the severe group patients [2.49 ng/ml (range 0.08–62.91 ng/ml)] were statistically higher than those in the mild group patients [0.81 ng/ml (range 0.03–23.39 ng/ml, p < 0.001)].