Biochemical Parameters in Pleural Fluids: New Contributions in the Etiologic Diagnosis of Body Fluids

Abstract

Objectives: The aim of this study was to evaluate the usefulness of different cutoffs applied to the cellularity and various biochemical parameters (BP) (metabolic and enzymatic) to contribute to the etiologic diagnosis of pleural fluids (PF). Design and Methods: We studied 150 samples from patients with pleural effusion, admitted to the Clinical Hospital. The cell count was total/mm3 (TCC) and differential. The simultaneous determination in pleural fluid (PF) and serum (S) of BP were performed on Roche Hitachi 917 autoanalyzer: Glucose (GLU), protein (PT), albumin (ALB), cholesterol (COL), triglycerides (TG), lactate dehydrogenase (LDH), creatine kinase (CK), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (FAL), amylase (AMI), total bilirubin (BT). Statistical methods were c² and Fisher. A value of p<0.05 was considered significant. Results: The most common cause of PF among transudates (T) was the heart failure (26%). In exudates (E), infections (43%) and cancer (25%) were the most frequent causes of PF. A TCC ≥ 500 cells/mm3 increased the detection of exudates without affecting the detection of transudate- type fluids. The PF / S ratio of LDH was the most useful among all BP in differentiating between T and E. PT, ALB, COL PF / S relations, and BT value > 0.5 mg / dl would be also suitable for differentiating T and E, and to a lesser extent PF / S for CK, AMI and SAAG. GLU value < 60 mg / dl showed no utility except in empyema. ALP, AST and ALT did not allow differentiating exudates from transudates. Conclusions: The use of a new cutoff for the TCC ≥ 500 cells / mm3 in the differential diagnosis of PF is suggested. Different BP contributed to the differentiation between E and T.