Comparison of protein values in cerebrospinal fluid by nephelometry and radial immunodiffusion

Various parameters of three radial immunodiffusion systems, a kinetic nephelometer and two laser nephelometers were compared in a measurement of IgG and albumin in cerebrospinal fluid. Greater precision for IgG and albumin determinations was found with two RID systems. Correlation coefficients between methods ranged from 0.71 to 0.94. The generally poor correlations of methods, combined with the results of accuracy studies employing WHO standard reference dilutions and proportional errors demonstrated by linear regression equations, illustrate graphically the need for standardization in the field of immunochemical determinations. Our preliminary studies of the IgG/Alb ratio in cerebrospinal fluid of multiple sclerosis patients agreed with the work of others. In each case, the ratio was elevated or borderline high.