CALCA and infection: Although a variety of biomarkers have been identified as presenting significant changes in their serum levels during a postoperative infection after spine surgery, including C-reactive protein (CRP), white blood cell count (WBC), erythrocyte sedimentation rate (ESR), body temperature (BT), and procalcitonin (PCT) [7, 15, 16], the sensitivity and specificity of each of these biomarkers were either not examined or were not high enough to always accurately distinguish infection versus non-infection.