++
The microangiopathic hemolytic anemias (also referred to as “thrombotic microangiopathies”) are a group of disorders in which RBC fragmentation takes place. The anemia is intravascular, producing hemoglobinemia, hemoglobinuria and, in severe cases, methemalbuminemia. The hallmark of the disorder is the finding of fragmented RBCs (schistocytes, helmet cells) on the peripheral blood smear (eFigure 15–17).
++++
These fragmentation syndromes can be caused by a variety of disorders (Table 15–8), including infections, rheumatic conditions, pregnancy, inherited complement pathway gene mutations, and advanced adenocarcinomas. Idiopathic thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome are the most important of these and are discussed in Part 16. Clinical features are variable and depend on the underlying disorder. Thrombocytopenia is present in most but not all thrombotic microangiopathies. Coagulopathy is variably present and depends on the underlying disorder driving the microangiopathy.
++
Chronic microangiopathic hemolytic anemia (such as is present with a malfunctioning cardiac valve prosthesis) may cause iron deficiency anemia because of continuous low-grade hemoglobinuria.
+
Leisring
J
et al. The clinical evaluation and management of thrombotic microangiopathy. Arthritis Rheumatol. 2024;76:153.
[PubMed: 37610060]
+
Raina
R
et al. Atypical hemolytic-uremic syndrome: an update on pathophysiology, diagnosis, and treatment. Ther Apher Dial. 2019;23:4.
[PubMed: 30294946]
+
Thomas
MR
et al. How I treat microangiopathic hemolytic anemia in patients with cancer. Blood. 2021;137:1310.
[PubMed: 33512445]
+
Thompson
GL
et al. Diagnosis and treatment of thrombotic microangiopathy. Int J Lab Hematol. 2022;44:101.
[PubMed: 36074708]