A FORMULA AND NOMOGRAM FOR THE ESTIMATION OF THE OSMOTIC PRESSURE OF COLLOIDS FROM THE ALBUMIN AND TOTAL PROTEIN CONCENTRATIONS OF HUMAN BLOOD SERA

Abstract

The colloid osmotic pressure and the total protein, albumin and globulin concns. of 128 samples of human serum from 53 normal and diseased individuals were determined, using the macro-Kjeldahl method for proteins, the method of Howe for separation of the fractions and the modification of the Krogh technic for osmotic pressure determinations recently described by Wells. An empirical formula for the calculation of the osmotic pressure has been derived from the data as follows: P = C(21.4 + 5.9A) where P is the osmotic pressure in mm. water and C and A are the total protein and albumin concentrations, respectively, in grams per 100 cc. The standard error of calculation is [plus or minus] 5%. A nomogram has been constructed to facilitate routine calculations. The specific osmotic pressure of serum appears to be a linear function of the albumin concn. alone, as indicated in the formula. Variations in the globulin over a wide range do not appear to affect the specific pressure of serum. The possible significance of this finding is discussed.