Abstract

Acquired hemolytic anemia can be divided into immune and non-immune mediated forms of hemolytic anemia.

Immune

Immune mediated hemolytic anaemia (direct Coombs test is positive)

- Autoimmune hemolytic anemia

- Warm antibody autoimmune hemolytic anemia

- Idiopathic

- Systemic lupus erythematosus (SLE)

- Evans' syndrome (antiplatelet antibodies and hemolytic antibodies)

- Cold antibody autoimmune hemolytic anemia

- Idiopathic cold hemagglutinin syndrome

- Infectious mononucleosis and mycoplasma (atypical) pneumonia

- Paroxysmal cold hemoglobinuria (rare)

- Alloimmune hemolytic anemia

- Hemolytic disease of the newborn (HDN)

- Rh disease (Rh D)

- ABO hemolytic disease of the newborn

- Anti-Kell hemolytic disease of the newborn

- Rhesus c hemolytic disease of the newborn

- Rhesus E hemolytic disease of the newborn

- Other blood group incompatibility (RhC, Rhe, Kidd, Duffy, MN, P and others)

- Alloimmune hemolytic blood transfusion reactions (i.e., from a non-compatible blood type)

- Drug induced immune mediated hemolytic anemia

- Penicillin (high dose)

- Methyldopa

Non-immune

Non-immune mediated hemolytic anemia (direct Coombs test is negative)

- Drugs (i.e., some drugs and other ingested substances lead to hemolysis by direct action on RBCs, e.g., ribavirin )

- Toxins (e.g., snake venom; plant poisons such as aesculin)

- Trauma

- Mechanical (from heart valves, extensive vascular surgery, microvascular disease, repeated mechanical vascular trauma)

- Microangiopathic hemolytic anemia (a specific subtype with causes such as TTP, HUS, DIC and HELLP syndrome)

- Infections (Note: Direct Coombs test is sometimes positive in hemolytic anemia due to infection)

- Malaria

- Babesiosis

- Septicemia

- Membrane disorders

- Paroxysmal nocturnal hemoglobinuria (rare acquired clonal disorder of red blood cell surface proteins)

- Liver disease

Drug induced hemolysis

Drug induced hemolysis has large clinical relevance. It occurs when drugs actively provoke red blood cell destruction. It can be divided in the following manner:

- Drug-induced autoimmune hemolytic anemia

- Drug-induced nonautoimmune hemolytic anemia

A total of four mechanisms are usually described, but there is some evidence that these mechanisms may overlap.