IgM Associated Cryoglobulinaemia

Cryoglobulinaemia is characterised by immunoglobulins which precipitate at temperatures be-low 37°C and redissolve on warming. Monoclonal IgM immunoglobulin may be associated with type I and II cryoglobulinaemia with underlying Waldenström macroglobulinemia, monoclonal gammopathy of undetermined significance or other non-Hodgkin lymphoma. We review the clinical characteristics, laboratory testing and suggest a management approach for monoclonal IgM associated cryoglobulinaemia. Laboratory testing is critical as even a minimal amount of measurable cryoglobulin may result in symptoms. Accurate detection of cryoglobulins may be challenging and care must be taken with preanalytical variables and repeat testing of monoclo-nal protein and cryoglobulins is indicated if clinical suspicion is high. Presentations range from asymptomatic disease to multisystem involvement so careful evaluation of the features and thorough interrogation of organ systems and the underlying clone is critical. Immediate man-agement is required for clinical red flag features. Due to their rarity, data to inform treatment decisions are scant and collaborative research is imperative to aid defining optimal treatment strategies.