Microangiopathic Haemolytic Anaemia

Microangiopathic haemolytic anaemia (MAHA) occurs when endothelial damage and / or fibrin deposition damages red cells, causing fragmentation. MAHA is a morphological finding which usually occurs in concert with a clinical thrombotic microangiopathy.

Blood film features:

• Schistocytes
• Microspherocytes
• Polychromasia with polychromatic macrocytes
• Thrombocytopaenia

Differential diagnosis

• Congenital
  • Congenital ADAMSTS13 deficiency
  • Congenital complement gene mutations
• Primary immune-mediated thrombotic microangiopathies
  • Thrombotic thrombocytopaenic purpura (autoantibody against ADAMSTS13)
  • Atypical haemolytic uraemic syndrome (autoantibody against complement factor H)
• Secondary thrombotic microangiopathies
  • Pregnancy-associated (HELLP, pre-eclampsia)
  • Malignant hypertension
  • Malignancy-associated
  • Transplant-associated
  • Autoimmune-associated
    • SLE
    • Catastrophic antiphospholipid syndrome
    • Glomerular disorders
  • Disseminated intravascular coagulation
  • Pancreatitis
  • Drug-induced TMA (e.g. quinine, gemcitabine, bleomicin, penicillin, oxymorphone etc.)
  • Mechanical haemolysis (e.g. cardiac valve haemolysis)
• Infection-associated
  • Haemolytic uraemic syndrome (Shiga toxin producing E. coli)
  • HIV-associated

Other resources:

• BCSH Guideline: Diagnosis and Management of TTP and other TMAs (2012)
• ISTH Draft Guideline: Diagnosis and Management of TTP (2019)
• ASH Image Bank: MAHA
• ASCO Post: MAHA Expert Review Case
• Syndromes of Thrombotic Microangiopathy (NEJM 2014)
• Transplant-Associated Thrombotic Microangiopathy (BMT 2017)
• Hereditary TTP (NEJM 2019)