Microangiopathic hemolytic anemia
Microangiopathic hemolytic anemia is a microangiopathic subgroup of hemolytic anemia caused by factors in the small blood vessels. It is identified by the finding of anemia and schistocytes on microscopy of the blood film.
Signs and symptoms
In diseases such as hemolytic uremic syndrome, disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and malignant hypertension, the endothelial layer of small vessels is damaged with resulting fibrin deposition and platelet aggregation. As red blood cells travel through these damaged vessels, they are fragmented resulting in intravascular hemolysis. The resulting schistocytes are also increasingly targeted for destruction by the reticuloendothelial system in the spleen, due to their narrow passage through obstructed vessel lumina. It is seen in systemic lupus erythematosus, where immune complexes aggregate with platelets, forming intravascular thrombi. Microangiopathic hemolytic anemia is also seen in cancer.Microangiopathic hemolytic anemia may be suspected based on routine medical laboratory tests such as a CBC. Automated analysers are designed to flag blood specimens that contain abnormal amounts of red blood cell fragments or schistocytes.
Causes
- Disseminated intravascular coagulation
- HELLP syndrome
- Thrombotic thrombocytopenic purpura
- Hemolytic uremic syndrome
- Atypical hemolytic uremic syndrome
- Cancer
- Malignant hypertension
- Scleroderma renal crisis
- Malfunctioning cardiac valves
- Kasabach–Merritt syndrome
- Insertion of foreign bodies
- Drugs
- Snake envenomation
- others diseases: eclampsia, renal allograft rejection, paroxysmal nocturnal hemoglobinuria, scleroderma, and vasculitides such as polyarteritis nodosa and granulomatosis with polyangiitis, antiphospholipid syndrome