<prompt> All the following in the Lights criteria are suggestive of exudative pleural effusion EXCEPTPleural fluid protein :serum protein ratio 0.5Pleural fluid ADA 16Pleural fluid LDH : serum LDH ratio 0.6Pleural fluid LDH two thirds of the upper limit of serum LDH  <response>: Lights criteria is used for distinguishing pleural transudate from exudate.Exudate is likely if one or more of the following criteria are met:-aPleural fluid protein:Serum protein ratio0.5;bPleural fluid LDH:Serum LDH ratio0.6;cPleural fluid LDHtwo-thirds of the upper limit of normal serum LDH. Reference:Davidsons medicine-22nd edition,page no:662. 