What are the causes of a pleural effusion?
A pleural effusion is a complication of various conditions. The following are some of the more common causes of a pleural effusion (but there are other rarer causes too). • Pneumonia (lung infection), tuberculosis, and tumours (cancers) may cause inflammation of the lung and pleura. This may cause fluid to build up into a pleural effusion. • Some arthritic conditions may cause inflammation of the pleura in addition to joint inflammation. For example, pleural effusion is an uncommon complication of rheumatoid arthritis and systemic lupus erythematosis (SLE). • Heart failure causes ‘back pressure’ in the blood vessels (veins) that take blood back to the heart. Some fluid may seep out of the blood vessels. Swelling of the legs with fluid is typical with heart failure, but a pleural effusion may also develop. • A low level of protein in the blood also tends to allow fluid to seep out of the blood vessels. For example, cirrhosis of the liver and some kidney diseases may cause a low level of
