The incidence of cryoglobulinaemia as determined by a turbidimetric method.

The incidence of cryoglobulinaemia was determined in 34 normal persons and in 56 sera from 52 patients with miscellaneous disorders. The turbidity of a sample of serum after 18 hours' refrigeration at 4 degrees C. was compared with a sample of the same serum incubated at 38 degrees C. for the same period of time. All refrigerated sera showed a greater turbidity than incubated sera. The abnormal sera showed a high degree of statistically significant correlation between total protein, gamma globulin, and the amount of cryoglobulinaemia. There was no significant correlation between cryoglobulinaemia and the age and sex of individuals or any of the other protein fractions. The results suggest that some degree of cryoglobulinaemia is of almost universal occurrence in various unrelated disorders and that this tendency to precipitate out in the cold is a characteristic of the gamma globulin group of proteins, especially when present in excess.