What is the most likely cause of anaemia in a patient who had a positive direct antiglobulin test?

In a patient with a positive direct antiglobulin test, the most likely cause of anemia is autoimmune hemolytic anemia (AIHA). The direct antiglobulin test, also known as the direct Coombs test, detects antibodies that are bound to the surface of red blood cells. A positive result indicates that the immune system is producing antibodies that attack and destroy the patient's own red blood cells, leading to hemolysis and subsequently anemia.

In AIHA, the underlying mechanism typically involves the production of these antibodies due to an autoimmune process, which can occur in isolation or as a response to other conditions such as infections, lymphoproliferative disorders, or certain autoimmune diseases. The hemolysis from this condition can cause a rapid drop in red blood cell levels, resulting in anemia.

While other options like delayed hemolytic transfusion reactions and drug-induced hemolytic anemia can also be associated with a positive direct antiglobulin test, those conditions usually have additional clinical contexts. Delayed transfusion reactions typically occur days to weeks after a transfusion and are often identifiable through a patient’s transfusion history. Drug-induced hemolytic anemia is more specific to cases where a drug triggers antibody formation, which may not always lead to a positive direct