DOI: 10.36347/sjams.2018.v06i07.003

Pages: 2620-2627

Enzymes are biological molecules that can be used as biomarkers of diseases. An old enzyme found in pleural fluid and not attracting significant attention in recent years as biomarker of disease, is lactate dehydrogenase (LDH). Thus, our purpose in this study was to determine the influence of age and sex on the diagnostic accuracy of pleural fluid total lactate dehydrogenase (P-LDH) levels in the differential diagnosis of pleural effusions. LDH assays were performed to assess diagnostic accuracy. A total of 308 samples (serum [n=137], pleural fluid [n=171]) were tested. The median P-LDH levels from patients with complicated parapneumonic pleural effusions (CPPE) and empyemas were not differentiated using the Kruskal-Wallis test (P>0.05). There was negative and statistically significant correlation between P-LDH level and sex in patients with CPPE/pleural empyema (rho = -0.661, P=0.0376, r2=0.4369). There was no significant correlation between P-LDH level and age dichotomized at 48 years (rho=0.170, P=0.5448, r2=0.0289). For the diagnosis of CPPE/pleural empyema, the best P-LDH cut-off values according to receiver operating curve (ROC) analysis were > 1188.0 U/L for males (area under the curve [AUC] 0.957 [95% CI 0.902-0.986]; P<0.0001) and > 1372.0 U/L (AUC 0.985 [95% CI 0.912-1.00]; P<0.0001) for females.