The Production of Edema and Serum Protein Deficiency in White Rats by Low Protein Diets

In 1895 Starling (2) first showed that the colloid osmotic pressure of the serum was proportional to the concentration of protein in it. He advanced the theory that decreased osmotic pressure in the serum was responsible for the deposition of water in the tissues. Disagreeing with Starling, Martin Fischer (3) claimed that edema resulted from alteration of the hydrogen ion concentration of blood and tissues which influenced the imbibition of fluid by the tissue proteins. Subsequent work has not supported Fischer’s theory, but has increasingly subst.antiated that of Starling. Govaerts (4) measured the colloid osmotic pressure of the serum of individuals, normal and otherwise, and found that an osmotic pressure lower than a certain figure was associated with a tendency toward edema (5). This lowered pressure could be caused by reduction in the total amount of protein, but especially by a loss of serum albumin (6). If the capillary pressure exceeded the osmotic pressure of proteins, water was deposited in the tissues. This held for edemas caused by stasis as well as others. Schade and Claussen (7) confirmed Govaert’s work in all respects by their “onkometer” methods. In this country, Epstein (8) found lowered serum proteins in certain cases of renal disease, especially the type called nephro-