What is the diagnosis and treatment for Erythrocytosis (increased red blood cell count)?

From the Guidelines

Erythrocytosis should be managed with phlebotomy as a first-line therapy, particularly in patients presenting with very high hematocrit (HCT) and clinical signs of hyperviscosity, as well as for long-term maintenance. This approach is supported by the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of Philadelphia chromosome-negative chronic myeloproliferative neoplasms, which emphasizes the role of phlebotomy in managing erythrocytosis 1. The goal of phlebotomy is to reduce the risk of thrombotic events by maintaining hematocrit below 45% in men and 42% in women.

Key considerations in the management of erythrocytosis include:

• Classification of erythrocytosis as primary (due to intrinsic bone marrow abnormalities) or secondary (resulting from increased erythropoietin production)
• Use of low-dose aspirin (81-100mg daily) to prevent thrombosis
• Cytoreductive therapy with hydroxyurea for high-risk patients with polycythemia vera
• Addressing the underlying cause in secondary erythrocytosis, such as oxygen therapy for hypoxic conditions or tumor removal for erythropoietin-secreting neoplasms
• Regular monitoring of complete blood counts and management of cardiovascular risk factors

Symptoms of erythrocytosis, including headache, dizziness, and visual disturbances, often improve with treatment as blood viscosity decreases 1. Untreated erythrocytosis increases the risk of thrombotic events, highlighting the importance of prompt and effective management.

From the Research

Definition and Characteristics of Erythrocytosis

• Erythrocytosis is characterized by an increased red blood cell mass, which can be primary or secondary, and congenital or acquired 2.
• Polycythemia vera (PV) is the most common primary acquired disorder, typically characterized by erythrocytosis, often with associated leukocytosis and thrombocytosis 3, 4, 5, 6.

Diagnosis and Investigation of Erythrocytosis

• The diagnostic criteria for PV have evolved over time and include an elevated hemoglobin or hematocrit level, abnormal results on bone marrow biopsy, and presence of the Janus kinase 2 genetic mutation 6.
• Measurement of the erythropoietin level is a first step in exploring the cause of erythrocytosis, with a low level indicating a primary cause and a normal or elevated level indicating a secondary etiology 2.
• Further investigation may include mutational testing, bone marrow biopsy, scans, and other tests as indicated by history and initial findings 2.

Treatment and Management of Erythrocytosis

• The main goal of therapy in PV is to prevent thrombohemorrhagic complications, with treatment options including phlebotomy, low-dose aspirin, and cytoreductive therapy with hydroxyurea or interferons 3, 4, 5, 6.
• Risk-adapted therapy is recommended, with high-risk patients requiring more aggressive treatment to prevent thrombosis 4.
• Modifiable risk factors, such as smoking and cardiometabolic disease, should be addressed to reduce the risk of thrombosis 6.

Prognosis and Complications of Erythrocytosis

• PV has a significant negative impact on overall mortality and morbidity, with risks of arterial and venous clots, symptoms of fatigue and pruritus, and conversion to leukemia and myelofibrosis 6.
• The presence of the JAK2V617F mutation is associated with an increased risk of complications, and reduction of the variant allele frequency is being evaluated as a treatment target 5.
• Leukemic transformation rates at 10 years are estimated at <1% for ET and 3% for PV, with fibrotic transformation rates slightly higher 4.