PLEURAL EFFUSIONS

SUMMARY

1. Pleural effusions can be transudative or exudative. Distinguished by comparing pleural fluid LDH & total protein to that in serum.

2. Transudate is due to systemic causes that affect the accumulation and absorption of pleural fluid. Causes: LV failure, cirrhosis, nephrotic syndrome.

3. Exudate is due to local causes. Causes: bacterial premmonia, cancer, PE.

4. Light’s criteria to differentiate b/w transudate and exudate: note that all 3 conditions must be met to be called a transudate, failing any 1 criteria makes it an exudate.

5. Transudative effusions can be misclassified as exudates during diuresis: use serum protein-pleural protein gradient (serum protein - pleural protein), with gradient > 3.1 g/dL being a transudate.

Reference(s)

Wilkinson, I. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].