• pleural effusions
• BTS guidelines

We are pleased to see that formal guidelines for the investigation of the previously neglected and sometimes difficult area of pleural effusions have been published.¹ There have been many publications concentrating on the distinction of exudative from transudative pleural effusions as a means of aiding the diagnostic process, but not necessarily focusing on the underlying clinical aetiology.

We were, however, disappointed to find that the Pleural Disease Guidelines Group did not appear to have taken specialist advice about the clinical biochemistry investigations. This means that some of the important methodological aspects have not been commented on. For example, it is important to appreciate that most of the assays currently used in NHS laboratories in the UK have not been optimised and validated for use in fluid other than serum/plasma and may give inaccurate results. A review of the biochemical aspects of pleural fluid analysis was recently published in the Annals of Clinical Biochemistry.² Although pleural fluid testing accounts for a very small percentage of laboratory work, this area requires close collaboration between the clinician and the laboratory to ensure that the most appropriate tests for answering the clinical question are selected, rather than adopting a blanket approach.

The advice that there is no requirement to test bilateral effusions which, in the clinical setting, are strongly suggestive of a transudative process unless there are atypical features or a failure to respond to treatment …