[Advantages and limitations of chemicomorphological study of pleural fluid]

A chemical-physical and morphological examination of 109 pleural samples taken from 66 patients showed that the most reliable laboratory tests for discriminating between an exudate and transudate were specific gravity, total effusion protein content and the effusion/serum protein ratio, while LDH and cell number seem less important. In the differential diagnosis of pleuritis, pleural fluid amylase assays are important only if certain well-defined diseases are suspected (particularly pancreatitis). In this case the assay is irreplaceable. Glucose assay may be carried out for a wider range of complaints although a review of the literature shows it to be always below 30 mg, particularly in cases of rheumatoid arthritis. A cytological examination offers a pathognomonic guide in the case of tumours and as a back-up to other checks for many other complaints.