Below text directly from Lee Altenberg’s website
Specimen Collection and Handling: Cryoglobulins come out of solution below body temperature. Serum must be obtained from clotted blood maintained at body temperature, from time of withdrawal. If blood is kept at lower temperatures, the cryoprecipitate may centrifuge out with the blood clot. The following procedure must be followed or the specimen is NOT acceptable.
CAUTION: Specimen is not acceptable when drawn on a patient receiving heparin or any other anti-coagulant. When a Dialysis/Apheresis patient has a catheter with heparin, 10 ml or more must be wasted (discarded) before specimen for Cryoglobulin is drawn. Peripheral stick is preferred. (Heparin is anti-Complementary and will therefore breakdown the Cryo immune complexes which contain complement producing a false negative or reduced Cryocrit.) Other anti-coagulants chelate Ca and deplete complement
Prepare transporting chamber: Select a receptacle that will maintain a fairly constant temperature. (Patient’s styrofoam pitchers with lids work very well)
Insert a thermometer, QC’d at 37°C, through the lid.
Add body temperature water to the receptacle. Start with water at 39°-41°C, so the temperature will not be below 37°C when received in the lab.
Use vacutainers, not glass syringes, to draw the blood.
Collect 20ml in red tops and place immediately into transporting chamber. If other tests are to be run in Immunopath, place all of the blood into the 37°C chamber.
Deliver to lab immediately.
Reject any specimen which does not comply with all of the criteria listed above. The specimen must be redrawn and must comply with all requirements.