52 Paroxysmal Nocturnal Hemoglobinuria (PNH)
Michelle To and Valentin Villatoro
Paroxysmal Nocturnal Hemoglobinuria is an acquired clonal disorder that starts at the stem cell level. Cells produced become susceptible and are destroyed by chronic complement-mediated hemolysis.1,2
Deficiency in glycosylphosphatidylinositol anchor proteins (GPIs). Normally, CD55 and CD59 act as complement regulators to prevent autologous complement-mediated hemolysis. Without GPIs, cells lack CD55 and CD59 and undergo spontaneous intravascular hemolysis.
Hemolytic episodes (Paroxysms) can be exacerbated by stressors such as inflammation or infections.
Bone Marrow Failure
Laboratory Results for PNH:1,3,4
If Iron Deficiency Present:
If Folate Deficiency Present:
If BM Failure Present:
If BM Failure:
If not BM Failure, may be:
-Normo to hypercellular
Iron stores: Decreased, or absent
Note: Any dysplastic findings may be indicative of MDS.
Same as iron deficiency anemia if patient becomes iron deficient.
Sucrose Hemolysis Test: Positive for hemolysis
Ham’s (Acidified Serum Lysis) Test: Positive
Flow cytometry (for CD55 and CD59)
Osmotic Fragility: Normal
Tests for IVH:
Indirect bilirubin: Increased
1. DeZern AE, Brodsky RA. Paroxysmal Nocturnal Hemoglobinuria. A Complement-Mediated Hemolytic Anemia. Hematol Oncol Clin North Am [Internet]. 2015 Jun 7 [cited 2018 Jun 26];29(3):479–94. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4695989/
2. Mastellos DC, Ricklin D, Yancopoulou D, Risitano A, Lambris JD. Complement in paroxysmal nocturnal hemoglobinuria: Exploiting our current knowledge to improve the treatment landscape. Expert Rev Hematol [Internet]. 2014 Oct 2 [cited 2018 Jun 26];7(5):583–98. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4383744/
3. Cochran-Black D. Hemolytic anemia: membrane defects. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 317-33.
4. Keohane EM. Intrinsic defects leading to increased erythrocyte destruction. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 367–93.