Urinothorax: case report and review of the literature with emphasis on biochemical diagnosis.

Urinothorax is a rare cause of transudative pleural effusion secondary to obstructive uropathy. We present a case of urinothorax after shock wave lithotripsy and review the literature. A total of 53 cases have been described previously, and in a few of them, the biochemical characteristics of the pleural fluid were detailed. In general, patients with urinothorax have low pH and glucose levels, and their lactate dehydrogenase level can be very high, resulting in misclassification of the effusion as an exudate. The average pleural fluid to serum creatinine ratio reported in 12 cases was 9.15 (range 1.09-19.8).