Analytical Considerations in the Investigation of Mixed Cryoglobulinemia

Schnabl et al. (1) recently presented a clinical case study of a patient with mixed cryoglobulinemia. It is important that such cases receive attention because cryoglobulinemia is often overlooked in diagnostic workups; however, several technical points regarding the analytical aspects of investigation require clarification.In their protocol for the investigation of cryoglobulins, the authors advocate the use of the “cryocrit” as a means of quantifying and typing the cryoglobulin in question. Their comments about “cryocrit” are, in fact, confusing. In their Fig. 1, they indicate that the cryocrit should be performed on “washed precipitate,” but in the Discussion they state that the cryocrit is the “(precipitate volume)/(total volume of serum sample).” It is not clear whether they are recommending centrifugation of the washed precipitate or the original chilled serum sample. Cryocrit is at best a crude semiquantitative method to estimate the amount …