Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (596 page)

   Altered pleural mechanics (e.g., late [chronic] atelectasis)

   Endocrine (e.g., hypothyroidism)

   Movement of fluid from abdomen to pleural space: Meigs syndrome (protein and specific gravity are often at transudate–exudate border but usually not transudate), urinothorax, cancer, pancreatitis, pancreatic pseudocyst

   Cirrhosis, pulmonary infarct, trauma, and connective tissue diseases are responsible for approximately 9% of all cases.

Exudates That Can Present as Transudates

   Causes

   PE (>20% of cases)—caused by atelectasis

   Hypothyroidism—caused by myxedema heart disease

   Malignancy—because of complications (e.g., atelectasis, lymphatic obstruction)

   Sarcoidosis—stages II and III

   Location

   Typically left sided: Ruptured esophagus, acute pancreatitis, rheumatoid arthritis. Pericardial disease is left sided or bilateral; it is rarely exclusively right sided.

   Typically right sided or bilateral: CHF (if only on left, consider that the right pleural space may be obliterated or the patient has another process [e.g., pulmonary infarction]).

   Typically right sided: rupture of amebic liver abscess.