What are the Light's criteria to determine if fluid in pleural effusion is exudate?

Updated: Jul 02, 2019
  • Author: James J Lamberg, DO; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Fluid is exudate if one of the following Light’s criteria is present: [1, 2, 3, 4]

  • Effusion protein/serum protein ratio greater than 0.5

  • Effusion lactate dehydrogenase (LDH)/serum LDH ratio greater than 0.6

  • Effusion LDH level greater than two-thirds the upper limit of the laboratory's reference range of serum LDH

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