296 Cholesterol in Pleural Effusions (Hamm et a!) Cholesterol in Pleural Effusions* A Diagnostic Aid

In this prospective study of7O patients with pleural effusion, the underlying disease could be identified in 62 cases. By predefined criteria, 31 of these effusions were classified as transudates and 31 as exudates. Pleural fluid protein con-tent, LDH activity and cholesterol level were measured to investigate their utility in differentiating the exudates from the transudates. Protein and LDH levels, and their pleural fluid-to-serum ratios, resulted in erroneous classification of II to 15 percent of the effusions. Mean cholesterol level in P leural effusions evolve in the course of a variety of diseases. They represent a common diagnostic task to the clinician. A correct diagnosis of the underlying disease is essential to rational management. In many cases, a diagnosis may be established without diffi-culty. However, despite employment ofextensive diag