Transudate
{{Short description|Extravascular fluid with a low protein and specific gravity}}
Transudate is extravascular fluid with low protein content and a low specific gravity (< 1.012). It has low nucleated cell counts (less than 500 to 1000 per microliter) and the primary cell types are mononuclear cells: macrophages, lymphocytes and mesothelial cells. For instance, an ultrafiltrate of blood plasma is transudate. It results from increased fluid pressures or diminished colloid oncotic forces in the plasma.
Transudate vs. exudate
{{Transudate vs. exudate}}
{{see also|Light's criteria|label 1 = Light's criteria for pleural effusions}}
There is an important distinction between transudates and exudates. Transudates are caused by disturbances of hydrostatic or colloid osmotic pressure, not by inflammation. They have a low protein content in comparison to exudates and thus appear clearer.The University of Utah • Spencer S. Eccles Health Sciences Library; WebPath images {{Cite web|url=http://library.med.utah.edu/WebPath/INFLHTML/INFL062.html |title=Inflammation |work= |accessdate=}}
Levels of lactate dehydrogenase (LDH){{Cite web |url=http://meded.ucsd.edu/isp/1994/im-quiz/pleuaden.htm |title=IM Quiz: Pleural Adenocarcinoma |website=UCSD School of Medicine, Educational Computing Department |url-status=dead |archiveurl=https://web.archive.org/web/20080916130507/http://meded.ucsd.edu/isp/1994/im-quiz/pleuaden.htm |archivedate=2008-09-16 }} or a Rivalta test can be used to distinguish transudate from exudate.{{cn|date=March 2021}}
Their main role in nature is to protect elements of the skin and other subcutaneous substances against the contact effects of external climate and the environment and other substances – it also plays a role in integumental hygiene.{{cn|date=March 2021}}
Pathology
The most common causes of pathologic transudate include conditions that:{{cn|date=March 2021}}
- Increase hydrostatic pressure in vessels: left ventricular heart failure,
- Decrease oncotic pressure in blood vessels:
- Cirrhosis (Cirrhosis leads to hypoalbuminemia and decreasing of colloid oncotic pressure in plasma that causes edema)
- Nephrotic syndrome (also due to hypoalbuminemia caused by proteinuria).
- Malnutrition (hypoalbuminism)