Transudate vs exudate

(JAMA 2014;311:2422)

Light’s criteria

基本上都是跟分子都是pleural，分母都是血 蛋大於五成、LDH大於六成或2/3

• protein/serum protein ratio greater than 0.5
• lactate dehydrogenase (LDH)/serum LDH ratio greater than 0.6
• LDH level greater than 2/3 two-thirds the upper limit of the laboratory’s reference range of serum LDH

exudate = TPeff/TPserum >0.5 or LDHeff/LDHserum >0.6 or LDHeff >²∕³ ULN of LDHserum; 97% Se, 85% Sp; best Se of all methods; however, will misidentify 25% of transudates as exudates; ∴ if clinically suspect transudate but meets criterion for exudate, confirm with test with higher Sp

Exudative criteria with better Sp:

choleff >55 mg/dL (95–99% Sp); choleff >45 mg/dL and LDHeff >200 (98% Sp); choleff/cholserum >0.3 (94% Sp); serum-effusion alb gradient ≤1.2 (92% Sp); serum-effusion TP gradient ≤3.1 (91% Sp)

CHF effusions:

TP may ↑ with diuresis or chronicity → “pseudoexudate”; alb gradient ≤1.2, choleff >60 mg/dL (Se 54%, Sp 92%) or clin judgment to distinguish (Chest 2002;122:1524)