title: Urinothorax: a new approach.
abstract: OBJECTIVE
  The presence of urine in the pleural space (urinothorax) is a rarely recognized cause of pleural effusion. To date, only 58 cases have been reported. In this article the features of urinothorax are analyzed, and clinical and biochemical characteristics are reviewed in order to propose a classification, founded on pathogenic criteria, that will be useful in achieving the diagnosis.
  
  
  RESULTS
  Recently reported cases of urinothorax provide a more detailed description of the biochemical characteristics that allow a better understanding of this entity.
  
  
  CONCLUSIONS
  Urinothorax can be divided into two categories: (1) obstructive urinothorax, due to bilateral obstructive uropathy; and (2) traumatic urinothorax, due to unilateral traumatic injury of the urinary system, mostly iatrogenic. In patients with urinothorax, the pleural effusion usually has the biochemical characteristics of a transudate, with a pH lower than 7.30 and a pleural fluid/serum creatinine ratio higher than 1. These characteristics are not always present, however, and individually are shared by a significant number of pleural effusions of different etiology.
authors.affiliation: Section of Pneumology, Hospital General Universitario, Elche, Spain. egpachon@hotmail.com
authors.forename: Eduardo
authors.initials: E
authors.lastname: Garcia-Pachon
authors.forename: Santiago
authors.initials: S
authors.lastname: Romero
mesh_terms: D003401:Creatine / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000652:urine; D010995:Pleural Diseases / Q000145:classification / Q000503:physiopathology* / Q000652:urine*; D010996:Pleural Effusion / Q000652:urine*; D011507:Proteinuria
chemical_list: D007770:L-Lactate Dehydrogenase; D003401:Creatine