Autoimmune hemolytic anemia, cold type

Autoimmune hemolytic anemia, cold type (also known as cold agglutinin disease or cold antibody hemolytic anemia) is a rare autoimmune disorder in which the body produces autoantibodies — typically IgM class — that bind to red blood cells at low temperatures (usually below 37°C). These cold-reactive autoantibodies, called cold agglutinins, cause red blood cells to clump together (agglutinate) and activate the complement system, leading to premature destruction of red blood cells (hemolysis). This process primarily affects the hematologic system but can have secondary effects on multiple organs due to chronic anemia and impaired circulation. Key symptoms include chronic hemolytic anemia with fatigue, weakness, pallor, and shortness of breath. Patients frequently experience acrocyanosis — a bluish discoloration of the fingers, toes, ears, and nose — triggered by cold exposure. Jaundice and dark urine may occur due to increased breakdown of hemoglobin. Episodes of acute hemolysis can be precipitated by cold temperatures or infections. The disease can be primary (idiopathic), which is most common in older adults, or secondary to underlying conditions such as lymphoproliferative disorders (e.g., lymphoma, Waldenström macroglobulinemia) or infections (e.g., Mycoplasma pneumoniae, Epstein-Barr virus). Treatment focuses on avoiding cold exposure, which is the most important preventive measure. Unlike warm-type autoimmune hemolytic anemia, cold agglutinin disease responds poorly to corticosteroids and splenectomy. Rituximab (an anti-CD20 monoclonal antibody) has become a mainstay of pharmacologic treatment, either alone or in combination with bendamustine for more severe cases. Sutimlimab, a complement inhibitor targeting the classical pathway (C1s), was approved by the FDA in 2022 for the treatment of hemolysis in adults with cold agglutinin disease, representing a significant advance in targeted therapy. Supportive care including folic acid supplementation and, when necessary, warmed blood transfusions may also be employed.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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