Cryoglobulin Sample Handling — SCE Rheumatology MCQ

Correct answer: D — Collect into a pre-warmed serum tube and maintain at approximately 37°C until clotting and serum separation

The correct answer is D. Cryoglobulins reversibly precipitate below body temperature, so blood must be collected using the laboratory's pre-warmed serum-sample protocol and maintained at approximately 37°C during transport, clotting and centrifugation until the serum has been separated. Cooling before separation may cause cryoglobulins to precipitate and become trapped with or removed alongside the cellular fraction, producing a falsely low or false-negative result. Only after warm serum separation is the serum cooled, usually to 4°C, to permit controlled cryoprecipitation. Routine room-temperature handling in A is therefore unreliable. EDTA plasma in C is not the standard specimen for serum cryoglobulin detection. Transport on ice in D promotes premature precipitation, while immediate room-temperature centrifugation and freezing in E do not provide the required warm pre-analytical phase.

Reference: Oxford University Hospitals NHS Foundation Trust, Immunology Laboratory. Cryoglobulins: specimen requirements. Last reviewed 1 July 2026. https://www.ouh.nhs.uk/immunology/diagnostic-tests/tests-catalogue/cryoglobulins/