Role of Pleural Fluid Cholesterol in Pleural Effusion

Abstract

Pleural effusion occurs when formation and accumulation of pleural fluid exceeds its absorption. It indicates an imbalance between pleural fluid formation and its removal. Pleural fluid accumulates in settings of increased hydrostatic pressure, increased vascular permeability, decreased oncotic pressure, increased intrapleural negative pressure and decreased lymphatic drainage. On the basis of pathophysiology, pleural effusion can be transudates or exudates. It is important to establish an accurate etiological diagnosis so that the patient may be treated in a rational manner. Using Light's criteria may need other extra investigations to differentiate transudates and exudates but using pleural fluid cholesterol (pCHOL) will help to diagnose them with only the pleural fluid analysis. Moreover the albumin or protein gradient will need serum as well as the pleural fluid investigations and will have more financial burden than just investigating pleural fluid cholesterol. Pleural cholesterol is thought to be derived from degenerating cells and vascular leakage from increased permeability. Thus pleural fluid cholesterol is one of the important investigations that can distinguish exudates from transudates. Routine use of pleural fluid cholesterol for classifying pleural effusion should be encouraged to improve the accuracy, sensitivity and specificity.