the diagnostic values of protein to lactate dehyrogenase ratio in serum and pleural fluid in exudate pleural effusions

introduction: different etiologies of pleural effusion are diagnosed based on serum and plural fluid characteristics. the aim of this study was to assess and compare the serum and pleural fluid protein to lactate dehyrogenase (pr/ldh) ratio in exudative pleural effusions. materials and methods: this study was conducted on 60 patients with exudative pleural effusion including: 20 cases with parapneumonic , 20 cases with tuberculosis (tb), and 20 cases with malignancy. the serum and pleural pr/ldh were measured and compared among 3 groups. result: the mean age of the patients was 55±19sd (years) and male to female ratio was 36/24. there was no statistically significant difference in mean age of the patients among 3 groups (p=0.08). there were statistically significant differences in serum and pleural pr./ldh ratios among groups ( p=0.04 and p= 0.1, respectively). additionally the comparisons of serum and pleural pr./ldh ratios between malignancy and tuberculosis groups were significant ( p=0.02 and p=0.001 , respectively). the serum and pleural pr./ldh ratios were higher in tb group. conclusion: the results of our study showed that serum and pleural pr./ldh ratio can be used in differentiating the etiology of exudative pleural effusion, but needs to be confirmed by larger study.