IL6 and infection: Under infection, interleukin 6 (IL‐6) usually appears in plasma at 30 min to 2 h after stimulation, reaches its peak at 4–6 h, and has a half‐life of about 4–6 h; Procalcitonin (PCT) usually appeared in plasma 2 to 3 h after stimulation, reached its peak at 12 to 24 h after infection, and its half‐life was about 20 to 28 h; C‐reactive protein (CRP), however, often appears in plasma at 6 to 8 h after stimulation, reaches its peak at 24 to 48 h, and has a half‐life of 19 h.