title: Light's criteria revisited: consistency and comparison with new proposed alternative criteria for separating pleural transudates from exudates.
abstract: OBJECTIVE
  The first objective was to assess the diagnostic value of new biochemical criteria proposed to discriminate pleural transudates from exudates and to compare their efficiency with those of Light's criteria. The second objective of the study was to assess the interstudy variability of the parameters repeatedly determinated in two different groups of patients with pleural effusion.
  
  
  METHODS
  We recorded clinical characteristics and final diagnoses and measured pleural fluid (PF) and serum levels of protein, LDH, cholesterol and cholinesterase of 243 patients with pleural effusion.
  
  
  RESULTS
  Sixty-one (25%) pleural effusions were transudates and 182 were exudates. The sensitivity (99%) and accuracy (96%) of Light's criteria were higher than those of the other criteria tested, although the differences with those of the PF LDH-cholesterol combination (96 and 93%) did not show statistical significance. Pleural LDH concentration was the criterion with the highest specificity (95%), being significantly higher (p < 0.05) than that of Light's criteria. The sensitivity, specificity and accuracy of most criteria tested did not vary when compared with those obtained in a study performed 5 years previously.
  
  
  CONCLUSIONS
  Light's criteria remain the criteria of choice for segregating exudates from transudates. Based on cost-efficiency reasons, the PF LDH-cholesterol combination appears as an alternative. Because both sets of criteria misdiagnose a substantial percentage of transudates, exceptions based on good clinical judgment and the complementary use of a more specific criterion, as the PF concentration of LDH, must be considered.
authors.affiliation: Servicios de Neumologia y Laboratorio, Hospital General Universitario, Alicante, España.
authors.forename: S
authors.initials: S
authors.lastname: Romero
authors.forename: A
authors.initials: A
authors.lastname: Martinez
authors.forename: L
authors.initials: L
authors.lastname: Hernandez
authors.forename: C
authors.initials: C
authors.lastname: Fernandez
authors.forename: A
authors.initials: A
authors.lastname: Espasa
authors.forename: A
authors.initials: A
authors.lastname: Candela
authors.forename: C
authors.initials: C
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002784:Cholesterol / Q000032:analysis; D002802:Cholinesterases / Q000032:analysis; D005069:Evaluation Studies as Topic; D005122:Exudates and Transudates / Q000737:chemistry*; D005260:Female; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000737:chemistry*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D002784:Cholesterol; D007770:L-Lactate Dehydrogenase; D002802:Cholinesterases