Flow cytometry is a sensitive and informative tool in PNH diagnosis and monitoring 1,2

ICCS guidelines recommend routine (1% PNH cell threshold) or high-sensitivity (0.01% PNH cell threshold) flow cytometry for patients at high risk of PNH 1

Early diagnosis is essential for improved patient management and prognosis 3,4


IDA = iron deficiency anaemia; MDS = myelodysplastic syndrome. *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 0.01 clone size.

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RBC analysis alone is not enough 1,2

Evaluation of RBCs alone may under-report clone size due to haemolysis and the dilution effect of transfusions 1-2,15,17

Granulocytes give the most accurate estimate of PNH lone size 1,2,11

Analysis of granulocytes and RBCs in a patient with PNH 1

PNH granulocyte clone: 55%

Adapted from Borowitz et al, 2010

PNH RBC clone: 6%

  • FLAER/CD24 combinations are recommended to detect PNH granulocytes 15
  • Low RBC clone size compared to WBC clone size is indicative of intravascular haemolysis 1

Ongoing Monitoring of PNH Clone Size is Important 1,2,16

  • Regular monitoring of patients with a previously identified PNH clone, is important 1,2
  • PNH clones can expand at any time 1,2

Adapted from Movalia et al, 2011

Study design: High sensitivity flow cytometry, with sensitivity up to 0.01%, was used to analyse 6,897 patients who were screened for PNH clones. The study included an examination of the change in PNH clone sizes among patients who had follow-up studies in 3–12 months.

Annual monitoring should be considered even for patients with a PNH clone size of < 0.1%.
For patients with a PNH clone size of > 1%, monitoring at least semi-annually is recommended.16

Find out more

    PNH = Paroxysmal Nocturnal Haemoglobinuria

  • References:
  • 1. Borowitz MJ, et al; for Clinical Cytometry Society.
    Cytometry Part B. 2010;78B:211-230.
  • 2. Parker C, et al. for International PNH Interest Group.
    Blood. 2005;106:3699-3709.
  • 3. Richards SJ, Barnett D. Clin Lab Med. 2007;27:577-590
  • 4. Socie G et al.Lancet 1996;348:573-577
  • 5. Rachidi S, et al. Eur J Intern Med. 2010;21:260-267.
  • 6. Hillmen P, et al. Am J Hematol. 2010;85:553-559.
  • 7. Brodsky RA. In: HoffmanR, Benz EJJr, Shattil SJ, et al,
    eds. Hematology: Basic Principles and Practice. 4th ed.
    Philadelphia, PA:Elsevier Churchill Livingstone; 2005:419-
  • 8. Dolezel Z, et al. Pediatr Nephrol. 2004;19:1177-1179.1
  • 9. Ballarín J, et al. Nephrol Dial Transplant. 2011;26:3408-
  • 10. Sharma VR. Clin Adv HematolOncol. 2013;11:1-11.
  • 11. Brodsky RA. Blood. 2009;113:6522-6527.
  • 12. Mohanty BD, De Castro CM.Am J Med. 2012;125:243-245.
  • 13. Meyers G, Parker CJ. Int J Hematol. 2003;77:125-132. 23.
  • 14. Brodsky A, et al. Exp Hematol Oncol. 2012;1:26.
  • 15. Sutherland R, et al. Am J Clin Pathol 2009;132:564-572
  • 16. Movalia K, et al. Blood 2011 118:1033.
  • 17. Hochsmann B, et al. Ann Hematol. 2011;90:887-899.
  • 18. Sutherland DR, et al. Cytometry Part B. 2012;82B:195-208.

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