Purpose

In individuals with systemic inflammation or bacterial infections, procalcitonin (PCT) levels rise in the circulation in response to bacterial endotoxins and inflammatory cytokines. PCT levels show an increase in levels within 2-6 hours and peak within 6-12 hours of infection. PCT levels have been found to correlate with the severity of bacterial infections and also with the probability of a positive blood culture, making it a clinically useful marker in the assessment of patients with possible sepsis or septic shock.

Moreover, studies have found that PCT release is blocked by cytokines that are characteristically present in the immune response to viral infections. For this reason, PCT is more specific to bacterial infections, and can aid in the differential diagnosis between nonbacterial illnesses and bacterial illnesses and sepsis. In circulation, PCT has a half-life of 25-30 hours when controlled by the host immune system or appropriate treatment.

PCT results may become elevated by causes other than systemic bacterial infection, including burns, trauma, autoimmune disorders or prolonged cardiogenic shock. Therefore PCT should not be used alone but always in conjunction with patient history and clinical signs and symptoms.

_{Source: Access Procalcitonin IFU #C53987 4/14/2021}