Rivalta test

For example, fluid accumulations due to congestive heart failure and liver failure (cirrhosis) are typically lower in protein content and are called transudates whereas fluid accumulations due to cancer and tuberculosis are typically higher in protein content and are called exudates.

[1] It is a simple, inexpensive method that does not require special laboratory equipment and can be easily performed in private practice.

The test was originally developed by the Italian researcher Rivalta around 1900 and was used to differentiate transudates and exudates in human patients.

[3] Using a pH 4.0 acetic acid solution, 8 types of proteins were identified in Rivalta reaction-positive turbid precipitates: C-reactive protein (CRP), Alpha 1-antitrypsin (alpha1-AT), Orosomucoid ((Alpha-1-acid glycoprotein or AGP)), haptoglobin (Hp), transferrin (Tf), ceruloplasmin (Cp), fibrinogen (Fg), and hemopexin (Hpx).

If the drop retains its shape, stays attached to the surface or slowly floats down to the bottom of the tube (drop- or jelly-fish-like), the Rivalta's test is defined as positive.