The corrected protein equation to estimate plasma colloid osmotic pressure and its development on a nomogram.

Examining the internal discrepancies of three equations (Landis and Pappenheimer 1965) which represent the relationship between colloid osmotic pressures (COP) and normal human plasma proteins, the authors derived a corrected globulin equation: COPglb = 1.3c + 0.14c2 + 0.006c3 (COP: mmHg, c: protein content, g/100 ml), instead of their COPglb = 1.6c + 0.15c2 + 0.006c3, when A/G (albumin-globulin ratio) = 1.1 as they had described. Revising the former globulin equation again, based upon the current estimate of A/G = 1.8, we derived a new globulin equation. Our new plasma equation, consisting of their albumin equation and our revised globulin equation, is COPpl = alpha (2.8c + 0.18c2 + 0.012c3) + beta (0.9c + 0.12c2 + 0.004c3), where alpha and beta stand for albumin and globulin fraction, respectively. The last, being generalized for plasma with any protein compositions, and closely corresponded to the values directly measured in normal human plasma with variable protein compositions, we developed it on a nomogram for practical use.