Lights Criteria


Light’s criteria is used to determine if an effusion is exudative or transudative. 

Fluid is exudate if one of the following Light’s Criteria Is Present:

  • Effusion of protein/serum protein ratio is great than 0.5
  • Effusion LDH/serum LDH ratio is greater then 0.6
  • Effusion LDH is greater than two-thirds the upper limit of lab’s reference range of serum LDH



Page Updated: 05.11.2019