Friday, August 21, 2015

Neutropenia and Thalassemia


  • patients with thalassemia frequently experience transient episodes of mild or moderate neutropenia irrespective of the chelation therapy they are on

Neutropenia due to Thalassemia

  • Splenomegaly invariably develops in the symptomatic thalassemias. Splenomegaly can worsen the anemia and occasionally cause neutropenia and thrombocytopenia.
  • neutropenia occurs significantly more often in patients with thalassemia who have not undergone splenectomy than in those who have
  • some viral infections, particularly parvovirus, may cause neutropenia independent of chelation therapy
  • Splenectomy does not causes neutropenia generally. Patients without a functioning spleen have a severe impairment in their ability to cope with specific infections [Pneumococcus, Meningococcus and Haemophilus influenzae]
  • In some cases (Felty’s Syndrome) splenectomy is actually able to reverse profound neutropenia

Neutropenia due to Iron Chelators

  • Approximately 6% of patients with thalassemia receiving deferiprone develop neutropenia
  • Due to the risk of agranulocytosis and associated rare deaths, weekly white blood cell counts are required for all patients receiving this drug.
  • Some studies showed that not all cases of mild neutropenia during deferiprone therapy develop into agranulocytosis, and suggests that many episodes of neutropenia may not be caused by deferiprone

Management

  • In deferiprone-treated thalassemia patients who develop agranulocytosis, therapy must always be interrupted
  • Neutropenia may precede the development of agranulocytosis. 
  • Measure the absolute neutrophil count (ANC) before starting deferiprone therapy and monitor the ANC weekly during therapy. 
  • Interrupt deferiprone therapy if neutropenia develops. 
  • If infection develops, interrupt deferiprone and monitor the ANC more frequently. 
  • Advise patients taking deferiprone to report immediately any symptoms indicative of infection
  • The present practice is to always discontinue therapy in all patients who experience a decline in neutrophils below 1.5 X 109 /L, irrespective of the potential cause of the neutropenia
  • For agranulocytosis (ANC < 0.5 x 109 /L), Consider hospitalization and other management as clinically appropriate. Do not resume Ferriprox in patients who have developed agranulocytosis unless potential benefits outweigh potential risks. Do not rechallenge patients

References:

  1. http://www.aafp.org/afp/2009/0815/p339.html
  2. http://www.tema.unina.it/index.php/jop/article/view/1282/1394
  3. http://thalassemia.com/documents/SOCGuidelines2012.pdf
  4. http://www.ncbi.nlm.nih.gov/pubmed/24330079
  5. http://thalassemia.com/documents/articles.El-Beshlawy-2014-deferiprone.pdf
  6. http://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021825lbl.pdf

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