Comparison of electroimmunodiffusion and radial immunodiffusion for measurement of IgG in the laboratory diagnosis of multiple sclerosis.

The detection of a supranormal quantity of immunoglobulin G (lgG) in cerebrospinal fluid is valuable in diagnosis of multiple sclerosis. In a previously published study of over 300 patients, including 46 patients with a clinical diagnosis of multiple sclerosis, 74% of the patients were found to have an abnormally high lgG value, expressed as a ratio of lgG/albumin, by the reliable method of electroimmunodiffusion. In the presont study the recently introduced method of radial immunodiffusion was compared with established electroimmunodiffusion technique in divided samples of cerebrospinal fluid from 49 patients with a wide range of lgG/albumin values. The correlation of the results obtained by these two methods was very good (r = 0.945), but the variance with radial immunodiffusion (±20 % ) is greater than with electroimmunodiffusion (± 15 % ). Two samples that exhibited increased values by the electroimmunodiffusion method were normal with the other technique. We condude that electroimmunodiffusion remains a slightly more accurate and sensitive technique, although radial immunodiffusion is simpler and requires less technician time.