The place of procalcitonin in differential diagnosis of pneumonia and pulmonary embolism

Aim: Procalcitonin (PCT) is a new and increasingly widely used marker in the diagnosis of bacterial infections. While it may be at low or negligible levels in healthy individuals, these levels rise in systemic bacterial infections. PCT has been shown to rise in pneumonia patients, though there are only very limited data in the literature regarding whether PCT levels also increase in pulmonary embolism (PE) patients. New studies are needed on this subject.Method: Patients presenting to the Karadeniz Technical University Medical Faculty Emergency Department between April and September 2009 with suspected PE or pneumonia and administered spiral CT were enrolled in this single-center, prospective, clinical study. Patients applying to the emergency department and with examination and laboratory findings (pulmonary imaging, C-reactive protein, D-dimer) within the diagnostic algorithm for PE and pneumonia and with suspected PE or pneumonia were recorded using standard data forms. Our study group of 176 cases was divided into four groups on the basis of the spiral CT results; 61 cases in Group A (PE only), 55 in Group B (pneumonia only), 12 in Group C (PE + pneumonia) and 48 in Group D (patients with diagnoses other than PE and pneumonia). At the end of the study, Group A, B, C and D patients? PCT levels and other parameters were compared.Results: Of the symptoms at presentation, only chest pain was significantly higher in the PE patients compared to the remaining groups (p=0.003). Both rales and rhonchi were significantly higher in the pneumonia patients than in the other groups (p<0.0001, p=0.003). Pulmonary parenchymal infiltration and mediastinal lymphadenopathy were significantly greater in the pneumonia patients compared to the other groups (p<0.0001, p=0.004). According to the ECG results, only T negativity in DIII (T3 finding), a deep S wave in DI, a pathological Q wave in DIII and SIQ3T3 findings stemming from T negativity were significantly higher in the PE patients compared to the other groups in such a way as to assist in the differentiation of PE and pneumonia (p=0.02, p=0.004).PCT levels among the study groups exhibited no differences that might be used in the differential diagnosis of PE and pneumonia (p>0.05). Optimal cut-off of 2011 pg/ml, sensitivity of 68.9, specificity of 41.1, NPV of 64.6 and PPV of 45.9 were determined for PCT in the differentiation of PE and pneumonia.Only D-dimer levels were significantly higher in PE patients than in the other study groups.Conclusion: Our findings indicate that PCT cannot be used as an assistant diagnostic tool in patients presenting to the emergency department with complaints such as dyspnea and fever and requiring differential diagnosis for PE and/or pneumonia. Our study stands in contrast to similar research in the literature, and its findings should now be evaluated with wider series studies.Key Words: Pulmonary embolism, pneumonia, procalcitonin.