PNH

PNH diagnosis is a matter of urgency1

PNH = Paroxysmal Nocturnal Haemoglobinuria

Thrombosis is the leading cause of death in PNH1

  • Thromboembolism (TE) accounts for 40-67% of deaths in PNH1
  • Chronic complement-mediated haemolysis puts PNH patients at continuous risk of thrombosis2
  • The first thrombotic event increases the risk of death 5 to 10 fold1
  • Both prophylactic and therapeutic anticoagulation are insufficient to prevent a TE in PNH patients3

High-sensitivity flow cytometry testing is essential in PNH diagnosis4

  • Recommended diagnostic guidelines for PNH, using high-sensitivity flow cytometry, were recently assessed for diagnostic efficiency5
  • The guidelines were found to be highly efficient, with a PNH detection rate of 14%5

High-Sensitivity Flow Cytometry testing, focusing on high risk patients, ensures that PNH is diagnosed without delay4,5

High-Sensitivity Flow Cytometry testing
† Anaemia, neutropenia, thrombocytopenia, or pancytopenia. ‡ Unusual sites include hepatic veins (Budd-Chiari syndrome), other intra-abdominal veins (portal, splenic, splanchnic), cerebral sinuses, and dermal veins. § Detects PNH cells down to at least a 0.01% clone size. IDA = Iron Deficiency Anaemia; MDS = Myelodysplastic Syndrome. This is intended as educational information for healthcare providers. It does not replace a healthcare provider’s professional judgement or clinical diagnosis. PNH Guidelines Download

Red blood cell (RBC) analysis alone is not enough4,7

  • Evaluation of RBCs alone may under-report clone size due to haemolysis and the dilution effect of transfusions4,7-9
  • Granulocytes give the most accurate estimate of PNH clone size4,7,10

    Analysis of granulocytes and RBCs in a patient with PNH4

    PNH granulocyte clone: 55%

    PNH granulocyte clone

    PNH RBC clone: 6%

    PNH RBC clone
    Adapted from Borowitz et al, 2010
  • Low RBC clone size compared to white blood cell clone size is indicative of intravascular haemolysis and/or transfusions4

Ongoing monitoring of PNH clone size is important4,6,7

  • PNH clones can expand at any time4,7
  • Annual monitoring should be considered for all PNH patients with an identified clone, even those with a clone size < 0.1%4,6
  • For patients with a PNH clone size > 1%, monitoring at least semi-annually is recommended6

Change in PNH clone size over 3 to 12 months6

In patients with an initial PNH clone size of 0.11% – 1% and 1.1% – 10%:

  • 40% Had an increase in clone size
  • 36% Had no change in clone size
  • 24% Had a reduction in clone size

Adapted from Movalia et al, 2011.


Study design: An analysis of the incidence of PNH clones in 6897 patients recommended for testing according to the guidelines from the ICCS and IPIG. High Sensitivity Flow Cytometry analysis, with sensitivity up to 0.01% was used to screen patients for a PNH clone (421/6897 patients had a clone detected). Changes in PNH clone size over a period of 3–12 months were assessed in 89 PNH-positive patients who had follow-up data available.

89/421 patients had follow up studies assessed over a period of 3-12 months. 64/89 patients had initial PNH clone sizes of 0.01% – 0.1% or 10.1 – 100%; one patient had a change in clone size category. 25/89 patients had initial PNH clones 0.11% – 1% and 1.1% – 10%; 16/25 (64%) had changes in PNH clone size category and 9/25 (36%) had no change in PNH clone size category.

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