The Importance of Complement C3 and C4 in Differantial Diagnosis of Pleural Effusions

Aim: We aimed to express the importance of pleural fluid C3-C4 levels and pleural fluid/serum C3-C4 ratio in transudativeexudative differentiation and to compare the C3-C4 levels in tuberculosis, malignancy and pneumonia effusions, thus detecting the diagnostic value. Material and methods: Of 70 patients studied, 25 had transudative and 45 had exudative effusions. Total protein, LDH and complement C3-C4 levels were measured for all. Results: In transudate-exudate distinction, the cut-off, sensitivity and specificity values are given below respectively for pleural fluid C3-C4 and for pleural fluid/serum C3-C4 levels. Pleural fluid C3: 50 mg/dL, 80%, 100%. Pleural fluid C4: 10 mg/dL, 82.2%, 88%. Pleural fluid/serum C3: 0.30, 77.8%, 96%. Pleural fluid/serum C4: 0.20, 88.9%, 72%. When the exudative subgroups were compared, both the pleural fluid C3-C4 levels and pleural fluid/serum C3 ratios were higher in tuberculosis pleurisy group. Conclusion: The findings suggest that the C3-C4 pleural values and the pleural fluid/serum C3-C4 ratios are encouraging approaches and they have a diagnostic value in tuberculous pleurisy.