PB2224 POLYCYTHEMIA VERA: A DIAGNOSTIC CHALLENGE
Authors: Gunes A. K. , Cinarsoy M. , Gozden H. E. 
Published: June 2019

Background:

In patients referred to hematology for investigating the etiology of the increased hemoglobin concentration and/or hematocrit, the first step is to find out whether there is a secondary cause of the polycythemia. Serum erythropoietin levels and JAK‐2 mutation screening are recommended after it is decided that polycythemia is not caused by a secondary cause. World Health Organization International Agency for Research on Cancer (WHO/IARC) has made major changes in 2016 on the diagnostic criteria for polycythemia vera. One of the major changes is lowered treshold hemoglobin/hematocrit levels. These values are use not only as diagnostic criteria, but also as the initiation of screening diagnostic tests for polycythemia. Thus, there has been a significant increase in the number of patients admitted to outpatient hematology clinics.

Aims:

Which patients should be investigated? Are there any preliminary characteristics or should all the patients be requested to JAK‐2 mutation or erythtropoetin leves ? 2‐ Which test should be requested first: serum erytropoetin level test or JAK mutation test? 3‐ When compared to WHO 2008, do the new diagnostic hb/htc criteria allow more patients to be diagnosed as polycthemia vera?

Methods:

243 Patients who applied to our clinic between 2016 and 2018 years, for high hemoglobin and/or hematocrit values according to WHO 2016 criteria, were analyzed retrospectively. All patients were tested for serum EPO levels and JAK‐2 exon 14 mutation status, and evaluated for the secondary causes of polycytemia. Normal values of lab for serum EPO levels are 3,5‐16,4 UI/L. All statistical analysis was made by SPSS version 22. Categorical variables were compared using χ2 or Fishers exact test.

Results:

243 patients were included in the study. Demographic data and laboratory results of the patients are summarized in Table‐1. 24 of 243 patients (%9,8) had positive JAK‐2 exon 14 mutation and diagnosed polycytemia vera. 30 of 243 (%12,3) had low serum Epo levels. (≤3,5 UI/L). 18 of 24 JAK‐2 positive patients had low EPO levels so there was a significant correlation between low serum EPO levels and JAK‐2 mutation status (p<0,001). There was no relationship between leukocytosis, thrombocytosis and JAK‐2 status. (p = 0,34). Age was another major factor related to JAK‐2 status. 20 of 24 JAK positive patients’ ages were 50 and above (p<0,001). 12 of these 20 patiens had a low Epo level, while 8 of them had a normal serum EPO values. (p<0,001). 4 of 24 JAK positive patients whose age was younger than 50 years, had a low EPO levels (p<0,001). Therefore, all of patentse diagnosed P.Vera below 50 years had a supressed EPO levels. When compared to P.Vera diagnosed patients who met the previous WHO‐2008 criteria (Hb ≥ 18,5‐Htc ≥ %55) (8/39, %20,5) and patients who had Hb values between 16,5‐18,4 g/dl (according to WHO‐2016 criteria)(16/196, %8,1), no significant difference was observed (p = 0,09) between two groups.

Summary/Conclusion:

This analysis concluded that in patients younger than 50 years old, the investigation of polycythemia must start with EPO levels. If EPO levels are suppresed, then JAK mutation testing can be performed. After the age of 50, both tests should be performed at the same time. If we had examined the patients according to WHO 2008, we couldn’t have diagnosed P.Vera for 16 patients whom hb levels were under 18,5 g/dl. On the other hand, we wouldn’t have tested 196 patients. Therefore, in population based patient series, the preliminary characteristics for further investigation to polyctemia must be established for cost effectiveness and labor.

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