This guideline aims to provide healthcare professionals with clear guidance on the investigation and management of thrombocytosis in both adult and paediatric patients.

The guidance may not be appropriate to all patients with thrombocytosis and in all cases individual patient circumstances may dictate an alternative approach.

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.