[Bivariate evaluation of laboratory findings: immunoglobulin G and albumin in cerebrospinal fluid (author's transl)].

Using radial immunodiffusion, albumin and immunoglobulin G were determined in non-preconcentrated cerebrospinal fluid from 127 controls and from 239 patients. In controls the concentrations of albumin and immunoglobulin G followed normal distribution. The two variables were correlated linearly (r = 0.60). The elliptic bivariate normal range was calculated, and was found to contain 95% of the paired values. As a clinical limit, this range discriminated more effectively between normal and altered pairs than the two one-dimensional normal ranges X+/-2 s, thus improving the evaluation of laboratory findings in the single case. Likewise in clinically defined groups of patients, bivariate evaluation of results provided additional evidence. In many distinct clinical syndromes, e.g. bacterial encephalomeningitis, polyneuropathy, amyotrophic lateral sclerosis, albumin and immunoglobulin G concentrations exhibited an especially close correlation, probably resulting from damage to the blood-cerebrospinal fluid barrier. However, no correlation of these two variables was detected in acute encephalomeningitis due to virus infection, and in multiple sclerosis: in these groups, immunoglobulin G concentrations were elevated independently of albumin. Since evidence is lacking as to the pathogenesis of multiple sclerosis, it seems noteworthy that the same phenomenon was observed in a well-defined group of viral infections.