Traditionally, polycythaemia has been used to identify a group of varied disorders with an increase in circulating red cells that are typified by a persistently raised haematocrit (Hct). Since only the red cell lineage is involved, the term erythrocytosis has more validity and will be used throughout this article. Polycythaemia will be retained in relation to the clonal disorder, polycythaemia vera (PV), in which three cell lineages are involved.

The purpose of this guideline is to provide a rational approach to the diagnosis, investigation and management of patients with an erythrocytosis. This will include recommendations on the management of PV, apparent and relative erythrocytosis, idiopathic erythrocytosis and the secondary erythrocytoses because of high oxygen affinity haemoglobin, hypoxia because of chronic lung disease, congenital cyanotic heart disease and postrenal transplantion.

This guideline has an update please see the information below.

Declaration of Interests

The BSH paid the expenses incurred during the writing of this guidance. None of the authors had conflicts of interest to declare. All authors have made a declaration of interests to the BSH and Task Force Chairs which may be viewed on request.