CALCA and Sepsis: For example, the initial PCT median (quartiles) concentration in patients who did not develop systemic inflammatory response syndrome (SIRS) or sepsis during their whole course was 0.53 ng/ml (<0.3 to 0.98 ng/ml), compared with those who did develop SIRS (0.77 ng/ml, <0.3 to 2.53; not significant), sepsis (2.21 ng/ml, 1.03–5.16; P = 0.003), severe sepsis (5.68 ng/ml, 1.82–9.56; P < 0.005) or septic shock (6.06 ng/ml, 2.69–13.4; P < 0.005).