Radioimmunoassay determinations of prostaglandin E in pleural effusions of varying causes

The concentrations of prostaglandin E(PgE) were measured in pleural fluid samples from 26 consecutive patients with pleural effusions of varying causes. The PgE concentrations were significantly increased in exudates when compared with transudates and provided a single measurement to separate these 2 classifications of pleural fluid. The highest concentrations of PgE were found in exudates associated with tuberculous pleuritis and metastatic lung cancer. Simultaneous measurement of pleural fluid and plasma PgE concentrations in patients with malignant effusions revealed that pleural fluid concentrations did not reflect plasma concentrations.