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[edit]
| Transudate vs. exudate | ||
|---|---|---|
| Transudate | Exudate | |
| Main causes | ↑ hydrostatic pressure, ↓ colloid osmotic pressure |
Inflammation-Increased vascular permeability |
| Appearance | Clear[1] | Cloudy[1] |
| Specific gravity | < 1.012 | > 1.020 |
| Protein content | < 2.5 g/dL | > 2.9 g/dL[2] |
| fluid protein/ serum protein |
< 0.5 | > 0.5[3] |
| SAAG = Serum [albumin] - Effusion [albumin] |
> 1.2 g/dL | < 1.2 g/dL[4] |
| fluid LDH upper limit for serum |
< 0.6 or < 2⁄3 | > 0.6[2] or > 2⁄3[3] |
| Cholesterol content | < 45 mg/dL | > 45 |
| Radiodensity on CT scan | 2 to 15 HU[5] | 4 to 33 HU[5] |
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.[6]
Levels of lactate dehydrogenase (LDH)[7] or a Rivalta test can be used to distinguish transudate from exudate.[citation needed]
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.[citation needed]
Pathology[edit]
The most common causes of pathologic transudate include conditions that:[citation needed]
- 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)
See also[edit]
References[edit]
- ^ a b The University of Utah • Spencer S. Eccles Health Sciences Library > WebPath images > "Inflammation".
- ^ a b Heffner J, Brown L, Barbieri C (1997). "Diagnostic value of tests that discriminate between exudative and transudative pleural effusions. Primary Study Investigators". Chest. 111 (4): 970–80. doi:10.1378/chest.111.4.970. PMID 9106577.
- ^ a b Light R, Macgregor M, Luchsinger P, Ball W (1972). "Pleural effusions: the diagnostic separation of transudates and exudates". Ann Intern Med. 77 (4): 507–13. doi:10.7326/0003-4819-77-4-507. PMID 4642731.
- ^ Roth BJ, O'Meara TF, Gragun WH (1990). "The serum-effusion albumin gradient in the evaluation of pleural effusions". Chest. 98 (3): 546–9. doi:10.1378/chest.98.3.546. PMID 2152757.
- ^ a b Cullu, Nesat; Kalemci, Serdar; Karakas, Omer; Eser, Irfan; Yalcin, Funda; Boyaci, Fatma Nurefsan; Karakas, Ekrem (2013). "Efficacy of CT in diagnosis of transudates and exudates in patients with pleural effusion". Diagnostic and Interventional Radiology. 20: 116–20. doi:10.5152/dir.2013.13066. ISSN 1305-3825. PMC 4463296. PMID 24100060.
- ^ The University of Utah • Spencer S. Eccles Health Sciences Library; WebPath images "Inflammation".
- ^ "IM Quiz: Pleural Adenocarcinoma". Archived from the original on 2008-09-16.