Respiratory: pleural effusion

Question 1

What are the two types of unliateral pleural effusion and how are the distinguished?

Answer 1

Transudate or exudate
Light’s criteria:
* Pleural fluid protein divided by serum protein is >0.5
* Pleural fluid lactate dehydrogenase (LDH) divided by serum LDH is >0.6
* Pleural fluid LDH >2/3 the upper limits of laboratory normal value for serum LDH

Question 2

What are common causes of a transudate pleural effusion?

Answer 2

• Congestive cardiac failure
• Liver cirrhosis
• Hypoalbuminaemia
• Nephrotic syndrome

Question 3

What are common causes of an exudate pleural effusion?

Answer 3

• Malignancy
• Pleural infection
• Pulmonary embolism
• Autoimmune pleuritis

Question 4

Which conditions can cause bilateral pleural effusions?

Answer 4

• Congestive cardiac failure
• Hypoalbuminaemia
• Renal failure
• Liver failure
• SLE and other autoimmune diseases
• Widespread malignancy including abdominal/pelvic malignancy
• Bilateral pulmonary embolus