Paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria

Updated: 07/14/2024

© Jun Wang, MD, PhD

 

General features

  • Clonal hematopoietic stem cell (HSC) disorder
  • Usually starts in early adults
  • Clinical triad of hemolytic anemia, pancytopenia, and thrombosis
  • Bone marrow failure may occur

Pathogenesis

  • Acquired mutation of PIGA (phosphatidylinositol N-acetylglucosaminyltransferase subunit A)



Clinical features

  • Dark urine at night with partial clearing during the day
  • Hemolysis at night triggered by acidosis during sleep
  • Anemia-related findings: fatigue, pain, organ dysfunction
  • May have aplastic anemia and myelodysplastic syndrome
  • Hemoglobinemia may cause renal insufficiency and pulmonary hypertension
  • Thrombosis: leading cause of mortality, affecting various sites: mesenteric, cerebral or dermal vessels.
  • Smooth muscle dystonias

o   Depletion of nitric oxide (NO) by free hemoglobin

o   Increased smooth muscle tone causing headache, dysphagia, abdominal pain, or erectile dysfunction

Laboratory findings

  • Features of normocytic anemia, with low reticulocyte count
  • Features of hemolysis
  • Leukopenia and thrombocytopenia
  • Elevated BUN and creatinine
  • Negative direct antiglobulin test

Diagnosis

  • Identification of granulocytes and RBCs lacking glycosylphosphatidylinositol (GPI)-linked proteins (CD55, CD59) in appropriate clinical setting

Management

  • Supportive, hematopoietic stem cell transplantation and complement inhibition
  • Prognosis depending on the severity of symptoms and the presence of complications

 

 

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