The normal proteins of plasma and serum do not precipitate in the cold. An aliquot of plasma and of serum are incubated for 24 hours at 1 degree C. If a precipitate develops in the serum, the specimen is centrifuged and the percent precipitate is reported. Negative specimens are kept at 1 degree C for 7 days and rechecked. All positive cryoglobulins are analyzed by immunofixation to determine if the precipitate is a monoclonal protein, polyclonal protein, or a mixed cryoglobulin. Precipitates that occur in plasma and not serum are reported as positive for cryofibrinogen. Cryofibrinogen-positive specimens are not quantitated or immunotyped. Slowly forming fibrin clots (as may occur in hemophilia) are distinguished from cryoprecipitates by their inability to redissolve on warming.(Lerner AB, Watson CJ: Studies of cryoglobulins. I. Unusual purpura associated with the presence of a high concentration of cryoglobulin [cold precipitatable serum globulin]. Am J Med Sci 1947;214:410-415)
Monday through Friday; 4 p.m.
Neg, 7 days/Pos, until reported