In health, very little protein is lost in stool, and the protein that is lost represents that coming from desquamated mucosal cells. Sometimes close to 50% of the plasma protein pool may be lost via the gut. This entity is called protein-losing gastroenteropathy, and there is a long list of causes for it (Umar and DiBaise, 2010). Whatever the cause, substantial loss of plasma protein through the gut requires damage to intestinal mucosal epithelium, obstruction to lymphatic drainage from the intestine, and an increase in pressure and or permeability of intestinal capillaries. Clinical findings include hypoalbuminemia, edema, and other findings attributable to the underlying cause. A diagnosis of protein losing gastroenteropathy is reached after eliminating other causes of hypoalbuminemia and by demonstrating increased clearance in stool of alpha-1 antitrypsin, a protein secreted by the liver but not degraded in the lumen of the gut. Alternately, the clearance of parenterally administered radionuclide labeled albumin in stool may also be documented to be abnormally high.   _{Your Comment}