Causes

• transudates

          - congestive heart failure
          - liver cirrhosis
          - nephrotic syndrome
          - hypoalbuminaemia

• exudates

 - malignant effusions 
 - parapneumonic effusions 
 - tuberculosis 
 - pulmonary embolism 

Note:

The commonest causes of pleural effusions are malignancy, heart failure, and infection

-	hospital wards in Spain b c	intensive care unit c
transudates
congestive heart failure	10% to 27%
liver cirrhosis	3%
nephrotic syndrome	2%
hypoalbuminaemia		8%
exudates
malignant effusions	30% to 48%	3%
parapneumonic effusions	11% to 17%	11%
TB	15% to 20%
PE	3% to 6%
collagen vascular disease	1%
trauma	1%
pancreatitis	0.3%
other	5%