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External Quality Assessment

External Quality Assessment

Undoubtedly, diagnosis is one of the areas most affected by the lack of sufficient scientific and medical knowledge on the RD field. Focussing on rare haematological diseases (RHD), differences in some core lab test for diagnosis have been observed across MS leading to a late diagnosis or even misdiagnosis, especially for the very rare diseases. 

In the context of ERN-EuroBloodNet, a collaboration was established with UKNEQAS  for a) the analysis of the state of the art of External Quality Assessment for the RHDs diagnosis and b) promote the establishment of schemes for RHD where gaps are identified. 

Pyruvate Kinase deficiency (PKD) is an example of a chronic RHD in which diagnosis can be delayed for years, can be misdiagnosis or even been labelled as haemolytic anaemia of unknown origin forever. Based on reference labs experience on PK activity results from non-expert centres/labs, some pitfalls on PK diagnosis have been observed:

  • No correlation between PK activities from non-experts and experts' centres
  • RBC package is not separated properly driving to leucocytes presence in the sample and increased PK activity
  • PK/HK ratio is not performed in non-expert labs leading to normal results in cases of high number of retyculocytes
  • Reference values for PK activity vary according to age and ethnical origin

In addition, there is a number of cases misdiagnosed, the main causes are:

  • Hereditary Spherocytosis, it is a more common cause of chronic hemolysis
  • Thalassaemia major, in cases of severe blood transfusion anemia
  • Liver abnormality, anaemia is considered secondary to the liver disease

In effort to tackle this gap the External Quality Assessment (EQAs) for PKD is under development in a collaboration between ERN-EuroBloodNet and the UK-External Quality Assessment Service.  Currently, it is on pilot phase involving 9 laboratories from 4 countries.

Euro Blood Net