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High-Sensitivity Testing for Paroxysmal Nocturnal Hemoglobinuria (PNH)



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May 2011

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder. Clinical features can vary greatly from patient to patient and during the course of the disease. There are three main clinical/pathophysiologic features:

  • Complement-mediated hemolysis that leads to hemoglobinuria, dysphagia, lethargy, chronic renal failure, pulmonary hypertension and anemia
  • Thrombotic tendency that can be life-threatening and often occurs in unusual anatomical locations, such as hepatic portal (Budd-Chiari Syndrome), splenic, or mesenteric veins
  • Underlying bone marrow failure, which is present to some degree in all patients, and can lead to severe aplastic anemia

Test #81156 PI-Linked Antigen, Blood by flow cytometry is a high-sensitivity assay that enables detection of small PNH populations in early PNH as well as in patients with bone marrow failure syndromes (aplastic anemia and myelodysplasia). The basis of this is collection of a high number of events, 150,000 – 500,000, and establishing normal cut-offs for the testing population. In addition, collection of a high number of events and more sophisticated gating strategies enable distinguishing partial loss of antigens (type II cells). Patients with large population type II RBCs are less likely to present with hemolysis.

Prevalence of PNH

  • Estimated 4,000 – 6,000 patients in United States
  • 5-year mortality up to 35%
  • All ages (median early 30s)
  • Progressive disease
  • Quality of life decreased

Testing Recommendations - International PNH Group

  • Coombs-negative acquired hemolytic anemia
  • Venous thrombosis at atypical sites
  • Hemoglobinuria
  • Dysphagia with elevated LDH
  • Aplastic Anemia (AA)
  • Myelodysplasia (MDS)

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