Substances isolated or purified from a solution by lowering the temperature or by freezing and then thawing. Cryoglobulin is demonstrated, and the antihaemophilic factor, Factor VIII, is obtained, in this way from blood plasma.
After cryoprecipitation, 60% of laboratories washed the sample, 81% resolubilized the cryoprecipitate at 37 [degrees]C, and 19% concentrated the sample before further analysis.
Of the 127 laboratories included for the postidentification phase, 50 (39%) reported the cryocrit, the total protein content, and/or the immunoglobulin concentration in the cryoprecipitate (quantitative); 48 (38%) answered negative/ positive only; and 29 (23%) provided additional information without reporting the cryoglobulin concentration in the cryoprecipitate (nonquantitative).
Forty-six of the 50 laboratories that provided a quantitative report and 55 of the 77 laboratories that provided a nonquantitative report performed immunofixation analysis on the cryoprecipitate.
For type I cryoglobulins, which are often present at concentrations >5 g/L, (1), reporting the presence or absence of an important visual cryoprecipitate that can be resolubilized is acceptable.
Of the 11 laboratories that provided reference values, only 3 (2%) applied cryoprecipitate-specific reference values, whereas the other 8 used reference values for serum proteins and/or immunoglobulins, which are not valid for the cryoprecipitate.