Diagnostic and prognostic role of procalcitonin in CAP

Despite advances in antimicrobial therapy, CAP remains the seventh leading cause of death in USA. Procalcitonin (PCT) is the pre-hormone of calcitonin, which is normally secreted by the C cells of the thyroid in response to hypercalcemia, its concentration was significantly increased in CAP. In lower respiratory tract infections, measuring serum PCT may aid physicians in differentiating between typical bacterial and non-bacterial causes of inflammation, using a cut-off value of 0.5 ng/mL and serum PCT guidance can reduce total antibiotic use. Furthermore, serum PCT is useful in predicting bacteraemia and in assessing disease severity in CAP patients. Aim of the work: To determine the usefulness of procalcitonin as a predictor of etiology and prognosis in patients with CAP. Patients and methods: This study was conducted at Tanta University Hospital over 50 patients with clinical and radiological findings compatible with CAP, 25 mild and moderate CAP and 25 severe pneumonia, thorough history taking, full Clinical examination, plain Chest X-ray, arterial blood gases, sputum samples for Gram stain and culture, blood samples for procalcitonin level measurement by monoclonal immunoluminometric assay was done. Results: There was a statistically significant rise of PCT in severe CAP as its mean levels were 4.7 ± 0.5 and 11.9 ± 27 ng/ml in mild and severe CAP groups respectively, with a positive correlation between the level of PCT and the severity of CAP. There was a statistically significant rise of PCT in typical pneumonia with a mean level of 9.9 ± 2.24 ng/ml in comparison to atypical pneumonia with a mean level of 3.2 ± 1.96. Conclusion: PCT measurement may provide an important indicator of severity for patients with CAP, also it can assess treatment response in these patients