Calculator

Light’s Criteria (for Exudative Pleural Effusions)

Pleural fluid protein	Pleural fluid protein unit
Serum protein	Serum protein unit
Pleural fluid lactate dehydrogenase (LDH)	IU/L
Serum LDH	IU/L
Upper limit of normal serum LDH (based on laboratory reference range)	IU/L
Reset
Result:

Formula
The effusion is exudative if one of the Light’s criteria has been met:

Pleural fluid protein/serum protein ratio > 0.5.
Pleural fluid LDH/serum LDH ratio greater than > 0.6.
Pleural fluid LDH level greater than 2/3 of upper limit of normal LDH level in serum.