Satisfying any ONE criterium means the pleural effusion is exudative:

•   Pleural Total Protein/Serum Total Protein ratio > 0.5
•   Pleural lactate dehydrogenase/Serum lactate dehydrogenase ratio > 0.6

• •   Pleural lactate dehydrogenase level > 2/3 upper limit of the laboratory’s reference range of serum lactate dehydrogenase.