Abstract
BACKGROUND Selective immunoglobulin A deficiency (SIgAD) is the most common primary immunodeficiency. However, most people with SIgAD are asymptomatic, and it is typically diagnosed during screening for blood donations or unexpected transfusion reactions. Screening programs for IgA deficiency have not yet been established, and the exact etiology of IgA deficiency remains unclear. CASE REPORT We report a case of SIgAD in a man who was diagnosed after a febrile non-hemolytic transfusion reaction (FNHTR) during erythrocyte transfusion for severe anemia. A 70-year-old man with a history of surgery for gastric carcinoid and sigmoid colon cancer presented to our hospital with persistent fatigue and general malaise for 2 months. A blood test revealed severe anemia with hyperbilirubinemia at the first visit to our hospital, and an erythrocyte transfusion was performed. A fever of 39.4°C with shivering was observed 30 min after the start of the transfusion. On day 20 after discharge, the serum IgA level was <3 µg/dL, indicating a high probability of IgA deficiency. He also tested positive for serum anti-IgA antibodies, leading to a diagnosis of SIgAD. CONCLUSIONS The cause of transfusion reaction should be immediately investigated, and the physician needs to learn about the epidemiology of transfusion reaction. Once the cause of transfusion reaction is identified, appropriate instruction should be provided for the patient to avoid transfusion reactions, and patients with SIgAD may benefit from wearing a medical alert bracelet.