Peritoneal and Pleural Fluid Chemistry Measurements Performed on Three Chemistry Platforms

Chemistry testing is requested for body fluid (BF) specimens despite the lack of assays approved by the US Food and Drug Administration (FDA). The criteria for categorizing fluids as transudate or exudate are not validated across analyzers.

To compare BF chemical analysis and classification by different analyzers.

We analyzed 10 pleural and 18 peritoneal fluids with corresponding plasma specimens using the Vitros 5,1 FS; Abbott ARCHITECT ci8200; and Roche Modular P platforms. Total protein (TP) and lactate dehydrogenase (LDH) were measured for pleural fluids. Light's criteria were applied. Albumin was measured for peritoneal specimens, and the plasma-ascites-albumin gradient was calculated.

TP results showed agreement. The Vitros LDH assay produced higher fluid:plasma ratios. Classification by Light's criteria resulted in 1 discrepancy (ARCHITECT). Albumin results showed agreement. There were 2 discrepant gradient interpretations (Vitros).

These data suggest that analyses of pleural and peritoneal fluids using these platforms are diagnostically interchangeable.