The serum viscosity and the serum proteins.

Equal weights of the various protein fractions in plasma affect the plasma specific gravity equally, whereas weight for weight the fractions exert differing influences on the plasma viscosity. Thus fibrinogen has a greater effect on the plasma viscosity than does globulin, which, in turn, has a greater effect than albumin (Bircher, 1921 ; Naegeli, 1931; Oberst, 1939; Cowan and Harkness, 1947). Working with mixtures of albumin and globulin, Naegeli (1931) and Nugent and Towle (1935) have shown that at a constant total protein content the viscosity of the mixture falls as the ratio of albumin to globulin rises, and vice versa. It was considered that perhaps, given the total protein content and the viscosity of a serum, it might be possible to calculate the albumin: globulin ratio. Thus, using the copper sulphate specific gravity method for estimation of the total serum protein level (Harrison, 1947) and a modified Ostwald viscometer for the estimation of the serum viscosity (Lawrence, 1950), the estimation might be completed in under 15 minutes per serum, a much more rapid test than either the Kjeldahl or the Biuret methods. The specific gravity of a seruim can be estimated to ± 0.0005 (± 0.18 g. %), and the serum viscosity ratio is accurate to ±0.2% (Lawrence, 1950). In fact, the estimation of the albumin:globulin ratio by this proposed method was not achieved.