A CBC algorithm combined with immature platelet fraction is able to identify JAK2 V617F mutation-positive polycythaemia vera patients.

Introduction: The recent lowering of the World Health Organisation (WHO) haemoglobin (Hb) and haematocrit (HCT) thresholds for diagnosis of polycythaemia vera (PV) has markedly increased the proportion of complete blood counts (CBC) that could be referred for haematologist review for comment, including advice on JAK2 V617F mutation analysis. The utility of an algorithm based on CBC indices and immature platelet fraction (IPF) to select cases for haematologist review was investigated.

Methods: IPF analysis was performed on 22 patients with known JAK2 V617F mutation and 41 patients who were negative for this mutation previously tested because of suspicion of PV. A reference range study for IPF was performed on 102 normal patients. The algorithm was applied to data from 163 358 CBC analyses to identify those most likely to have PV for review by a haematologist.

Results: The CBC algorithm and IPF requirement were satisfied by 47 patients (0.03%), eight of whom were known to have myeloproliferative disorders; the remaining 39 were referred for haematologist review.

Conclusion: Utilising the algorithm enables identification of patients with a high likelihood of PV for haematological review. Large numbers are able to be screened efficiently and cost-effectively. Some patients with masked PV are able to be detected before clinical presentation.