CALCA and bacterial infectious disease: Serum PCT is raised in bacterial infections, but remains low in viral infections and nonspecific inflammatory diseases.[7] Many studies showed that PCT was a helpful biomarker in detecting bacterial infections.[8] PCT-guided antibiotic stewardship in persistent bacterial infections may reduce the duration of antibiotic therapy.[9] Liver is one of the tissues that produce PCT in response to bacterial infections,[10] leading to speculation as to whether PCT levels would be lower in patients with impaired liver function.