Plasma Proteins and Edema

In health, about four fifths of the solids of the plasma consist of plasma proteins. Their approximate percentages are as follows: total protein, from 7 to 8; albumin, from 4 to 5; globulin, from 1.5 to 3.5; fibrinogen, from 0.1 to 0.25; albumin-globulin ratio, 37. The colloidal osmotic pressure of the blood plasma is from 25 to 30 mm. of mercury and is maintained largely by the plasma proteins, as was first revealed by Starling.1The colloidal osmotic pressure of the blood plasma (the totality of pressure with which the colloid tends to retain water) is not necessarily proportional to the total concentration of plasma protein, because the individual plasma proteins have different colloidal osmotic pressures. The total amount of protein may remain the same, while variations of the relative proportions of the different proteins may change the osmotic pressure. The colloidal osmotic pressure exerted by the smaller molecular