Serum procalcitonin level: clinical significance.

Procalcitonin, a propeptide of calcitonin, is an important host response biomarker indicative of infection. In particular, it aids in assessing the severity of infection and its prognosis [2, 3]. Using this severity marker to differentiate two infectious diseases seems unjustified. Both the diseases can have varying degrees of severity and may also be confounded by factors such as immunocompromised status and presence of comorbidities, such as post surgery [4], trauma [5], acute exacerbations of chronic obstructive pulmonary disease and acute coronary syndrome, which can alter procalcitonin levels. Clinical presentations, pattern of radiological involvement and sputum examination still remain the gold standard, as well as cost-effective measures to differentiate PTB and CAP.