Investigating thrombocytosis

Abstract

• Thrombocytosis is more often reactive than due to a primary haematological disorder. • Diagnosing the cause of thrombocytosis is important to enable appropriate management. • The cause of thrombocytosis can often be determined by reviewing previous full blood counts, considering any other abnormalities on the full blood count and taking a detailed history. • There are a small number of patients with thrombocytosis in whom the cause will remain uncertain. • Some laboratory tests may assist in difficult cases; however, there is none that will definitely differentiate reactive from autonomous thrombocytosis. • Patients with a primary haematological disorder and those in whom the diagnosis has not been determined should be referred to a haematologist.