Classification of PNH
| Category . | Rate of intravascular hemolysis* . | Bone marrow . | Flow cytometry . | Benefit from eculizumab . |
|---|---|---|---|---|
| Classic | Florid (markedly abnormal LDH often with episodic macroscopic hemoglobinuria) | Cellular marrow from erythroid hyperplasia and normal or near-normal morphology† | Large population (>50%) of GPI-AP–deficient PMNs‡ | Yes |
| PNH in the setting of another bone marrow failure syndrome§ | Mild (often with minimal abnormalities of biochemical markers of hemolysis) | Evidence of a concomitant bone marrow failure syndrome§ | Although variable, the percentage of GPI-AP–deficient PMNs is usually relatively small (<50%) | Typically no, but some patients have relatively large clones and clinically significant hemolysis and may benefit from treatment |
| Subclinical | No clinical or biochemical evidence of intravascular hemolysis | Evidence of a concomitant bone marrow failure syndrome§ | Small (<10%) population of GPI-AP–deficient PMNs detected by high-resolution flow cytometry | No |
| Category . | Rate of intravascular hemolysis* . | Bone marrow . | Flow cytometry . | Benefit from eculizumab . |
|---|---|---|---|---|
| Classic | Florid (markedly abnormal LDH often with episodic macroscopic hemoglobinuria) | Cellular marrow from erythroid hyperplasia and normal or near-normal morphology† | Large population (>50%) of GPI-AP–deficient PMNs‡ | Yes |
| PNH in the setting of another bone marrow failure syndrome§ | Mild (often with minimal abnormalities of biochemical markers of hemolysis) | Evidence of a concomitant bone marrow failure syndrome§ | Although variable, the percentage of GPI-AP–deficient PMNs is usually relatively small (<50%) | Typically no, but some patients have relatively large clones and clinically significant hemolysis and may benefit from treatment |
| Subclinical | No clinical or biochemical evidence of intravascular hemolysis | Evidence of a concomitant bone marrow failure syndrome§ | Small (<10%) population of GPI-AP–deficient PMNs detected by high-resolution flow cytometry | No |
Based on recommendations of the International PNH Interest Group.3
Based on macroscopic hemoglobinuria, serum LDH concentration, and reticulocyte count.
Karyotypic abnormalities are uncommon.
Analysis of PMNs is more informative than analysis of RBCs because of selective destruction GPI-AP–deficient RBCs.
Aplastic anemia or low-risk myelodysplastic syndrome.