PCT is a prohormone of calcitonin. In healthy individuals, PCT is produced from parafollicular cells of the thyroid and neuroendocrine cells of the lung and intestine.However, in patients with a bacterial infection, PCT is produced from numerous organs in the body. PCT is classified as a 'hormokine' given its relation with both the hormone calcitonin and the inflammatory cascade. The standard reference value of PCT is ≤ 0,15 ng/ml. Localized infections usually show a level between 0,15 and 2.0 ng/ml; while PCT level ≥ 2.0 ng/ml is generally associated with systemic bacterial infection/sepsis or severe localized bacterial infection. PCT levels increase within 2-4 hours of infection, and the maximum level is reached by 6-8 hours [39] . Once the infection is controlled, PCT levels half-life is about 20-24 hours. PCT levels persist as long as the inflammatory process continues, and the level correlates with the severity of sepsis. PCT is produced in response to endotoxins or inflammatory mediators released in response to bacterial infection. PCT levels correlate with the severity of the infection and help discriminate patients with infectious and non-infectious systemic inflammation, differentiate bacteria from viral and fungal infections, and help identify bacterial superinfection in patients with a viral infection. Studies showed that higher PCT on the day of admission to ICU is associated with increased risk of progression to severe sepsis and septic shock [40] . In critically ill patients, the high maximum PCT level and a PCT increase for one day are independent predictors of 90-day mortality [41] . PCT values help decide about the need for antibiotics and the duration of antibiotic therapy [42] .Serial measurement of PCT in sepsis can guide antibiotic treatment and helps in therapeutic decision-making. Consequently, PCT can be used as a diagnostic test and prognostic marker to assess the response to treatment and a marker of the severity of sepsis and associated mortality.Various studies [43,44,45] have shown that PCT is superior to CRP in identifying and assessing the severity of sepsis and in diagnosing bacterial infection in critically ill patients. PCT is more sensitive and specific for bacterial infection than CRP. PCT is useful in predicting the results of blood culture in patients with a critical illness. Low levels of PCT help rule out sepsis because of their high negative-predictive value. PCT levels rise earlier than those of CRP, helping in early anticipation of sepsis diagnosis 24-48 hours before the CRP levels would.PCT can be falsely negative in people with localized infection, infection with atypical bacteria, and patients on steroids. On the other hand, PCT levels can be increased in patients with severe trauma, surgery, or cardiac arrest. TREATMENT [1,2,3] Recommendations 