Edema due to decreased intravascular osmotic pressure
This diagram depicts the pathogenesis of edema formation due to decreased plasma colloidal osmotic pressure. Capillary blood contains a decreased quantity of colloids (protein-white circles) due to either decreased hepatic synthesis of these proteins or increased protein loss through the kidney or gastrointestinal tract. As a result of the hypoproteinemia, fluid and crystalloids fail to be reabsorbed at the venous end of the capillary and accumulate in the interstitium as edema.
Reduction in serum albumin decreases intravascular oncotic pressure and causes edema.
Most of this dog’s liver has been replaced by neoplastic tissue. This affects serum protein content by compromising the liver’s ability to synthesize albumin. With decreased production of albumin the plasma colloidal osmotic pressure decreases and edema occurs.
More commonly occurring conditions that may cause hypoproteinemia are renal and gastrointestinal disease. In these diseases, hypoproteinemia occurs due to loss of protein through urine (protein-losing nephropathy such as amyloidosis) or feces (protein-losing enteropathy such as intestinal lymphosarcoma).
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