Related Experiment Video
Updated: Mar 10, 2026

Flow Cytometry Analysis of Tissue Factor Expression in Human Platelets
Published on: November 22, 2024
Approach to patients with essential thrombocythaemia and very high platelet counts: what is the evidence for
Lorenzo Falchi1, Prithviraj Bose2, Kate J Newberry2
1Division of Hematology/Oncology, Columbia University Medical Center, New York, NY, USA.
Treatment of essential thrombocythaemia (ET) is directed at decreasing the risk of complications of the disease, including arterial and venous thrombosis and bleeding episodes. Established risk factors for vascular events in patients with ET include advanced age (>60 years) and prior history of thrombosis or haemorrhage. The role, if any, of other potential risk factors, including cardiovascular risk factors, leucocytosis, high haematocrit, and JAK2 V617F has been analysed in multiple studies. The impact of thrombocytosis on the risk of vascular events has also been investigated. Many clinicians consider an elevated platelet count to be a risk factor for thrombosis or, when extreme, bleeding and utilize this as a criterion to start cytoreductive therapy. However, the relationship between thrombocytosis and vascular events is controversial and solid evidence to support the use of cytoreductive therapy in ET patients who have no other risk factors is lacking. In this review, we discuss current treatment recommendations for patients with ET, the biology underlying vascular events and risk factors thereof. We then review the evidence on the management of patients with ET and extreme thrombocytosis.
Treatment of essential thrombocythaemia (ET) is directed at decreasing the risk of complications of the disease, including arterial and venous thrombosis and bleeding episodes. Established risk factors for vascular events in patients with ET include advanced age (>60 years) and prior history of thrombosis or haemorrhage. The role, if any, of other potential risk factors, including cardiovascular risk factors, leucocytosis, high haematocrit, and JAK2 V617F has been analysed in multiple studies. The impact of thrombocytosis on the risk of vascular events has also been investigated. Many clinicians consider an elevated platelet count to be a risk factor for thrombosis or, when extreme, bleeding and utilize this as a criterion to start cytoreductive therapy. However, the relationship between thrombocytosis and vascular events is controversial and solid evidence to support the use of cytoreductive therapy in ET patients who have no other risk factors is lacking. In this review, we discuss current treatment recommendations for patients with ET, the biology underlying vascular events and risk factors thereof. We then review the evidence on the management of patients with ET and extreme thrombocytosis.
Related Concept Videos
Venous Thrombosis III: Interprofessional Care
Treatment for Pulmonary Arterial Hypertension: Receptor Tyrosine Kinase Inhibitors and Calcium Channel Blockers
TKIs, such as imatinib (Gleevec), are particularly effective in tackling the growth and mitogenic factors that become upregulated in PAH patients. These factors contribute to the...
Pulmonary Embolism II: Diagnostic Studies and Interprofessional Care
Venous Thrombosis IV: Nursing Management
Anticoagulant Drugs: Low-Molecular-Weight Heparins
Structure and Function of Platelets
Platelets are continually replenished, circulating in the bloodstream for 9-12 days before being removed by phagocytes, primarily in the spleen. A microliter of circulating blood contains between 150,000 and 450,000...

