Both are fluids that can occur in the body during inflammation or changes in liquid-solid (oncotic-hydrostatic) pressures.
Transudate is transparent, because it is clear and has a low protein content. It comes from a deranged balance of oncotic-hydrostatic pressures. As a generalisation, think systemic disease.
Exudate involves extruded proteins. It has a comparatively high protein content. As a generalisation, think local inflammation or malignancy.
A pleural effusion can involve transudate or exudate. Light’s Criteria is used to determine which is the case.
- Exeter Clinical Laboratory. Blood Sciences Test / Transudate or Exudate. Retrieved 19 March 2017, from http://www.exeterlaboratory.com/test/transudate-or-exudate/
- Life in the Fast Lane Medical Blog. Pleural Fluid Analysis. Retrieved 19 March 2017, from https://lifeinthefastlane.com/investigations/pleural-fluid-analysis/
- American Family Physician. (2006). Diagnostic Approach to Pleural Effusion in Adults. Retrieved 19 March 2017, from http://www.aafp.org/afp/2006/0401/p1211.html