In a series of 86 elderly patients the measurement of pleural fluid protein was found to be of limited value in distinguishing exudates from transudates, although levels above 49 gil were all found to be exudates. However, the difference in mean pleural fluid proteins in the two groups when analysed statistically was highly significant. In addition, there was a significant difference between the means within the exudative group when analysed in groups according to aetiology.
Correcting for plasma albumin values did not improve discrimination between exudates and transudates despite a significant correlation between albumin and pleural fluid protein concentration.
