RESUMO
Cold autoimmune hemolytic anemia (cAIHA) is a form of autoimmune hemolytic anemia (AIHA) that most often involves agglutinin antibodies that specifically react to cold temperatures. This process most commonly involves an immunoglobulin M (IgM)-mediated agglutination of erythrocytes and can result in complement-mediated hemolysis, which can range greatly in severity from case to case. Here, we present a case of cAIHA in a 64-year-old male who presented with rapidly progressive and severe hemolytic anemia, which resulted in irreversible decompensation. This case highlights the importance of maintaining a high index of suspicion for cAIHA in patients older adult patients with a previous history of autoimmune hematologic diseases presenting in a rapidly progressive hemolytic state, which can allow for prompt diagnosis, treatment, and mitigation of adverse outcomes.