A 56-year-old man comes to the office due to an episode of transient right eye blindness that lasted an hour. He has had no weakness in his extremities or speech changes. He last saw a physician 3 years ago. The patient has smoked a pack of cigarettes daily for 30 years. Temperature is 37 C (98.6 F), blood pressure is 160/94 mm Hg, pulse is 78/min, and respirations are 14/min. Pulse oximetry is 98% on room air. BMI is 32 kg/m2. There is no carotid bruit. Facial plethora is present. Cardiopulmonary examination is normal. Abdominal examination reveals splenomegaly. There is no lower extremity edema, and peripheral pulses are intact. Laboratory results are as follows:
Complete blood count Hemoglobin 20 g/dL Hematocrit 60% Platelets 545,000/mm3 Leukocytes 13,800/mm3 Serum chemistry Sodium 141 mEq/L Potassium 3.6 mEq/L Blood urea nitrogen 16 mg/dL Creatinine 0.7 mg/dL Glucose 96 mg/dL
In addition to counseling about smoking cessation, which of the following is the best therapy for this patient?
Polycythemia vera | |
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RBC = red blood cell. | |
Polycythemia vera (PV) is a clonal myeloproliferative disorder characterized by erythrocytosis. Most cases are associated with a JAK2 mutation. Patients are often asymptomatic at diagnosis but may present with symptoms related to increased blood viscosity (eg, transient visual disturbances, hypertension, thrombosis) and increased red blood cell (RBC) turnover (gouty arthritis). Itching after warm showers (aquagenic pruritus) is common. Physical examination often shows facial plethora (ruddy cyanosis) and splenomegaly. Unlike other causes of erythrocytosis (eg, chronic hypoxia, erythropoietin [EPO]-producing tumors), patients with PV usually have normal oxygen saturations and low EPO levels. Complete blood count often shows an increase in all 3 cell lines.
Serial phlebotomy is the mainstay of treatment for PV; it creates a relative iron deficiency and reduces hematocrit levels to normal range. Bone marrow suppressive drugs (eg, hydroxyurea) may be added in patients at high risk of thrombosis (eg, previous thrombosis, advanced age).
The terms polycythemia and erythrocytosis are often used interchangeably; however, not all polycythemia is truly erythrocytosis. Polycythemia implies a laboratory finding of elevated hematocrit and may be diagnosed as relative (usually due to a reduction in plasma volume) or absolute (due to increased RBC production). Only absolute polycythemia involves erythrocytosis (increased RBC mass). Absolute polycythemia/erythrocytosis is seen in patients with PV and secondary polycythemia (eg, chronic hypoxia, EPO-secreting tumors).
(Choice A) Anticoagulation is used in the treatment of thromboembolic disease, antiphospholipid antibody syndrome (APLAS), and PV with evidence of thrombotic event. Transient ocular blindness in PV is not an indication for anticoagulation as it is due to microvascular sludging (from severe erythrocytosis), not thromboembolism. APLAS would not cause hypertension, facial plethora, splenomegaly, or thrombocytosis.
(Choice C) Plasma exchange removes toxic substances (eg, autoantibodies, immune complexes, endotoxins, cryoglobulins) from plasma. It is used in conditions such as thrombotic thrombocytopenic purpura (characterized by microangiopathic anemia and thrombocytopenia) and hemolytic uremic syndrome (characterized by acute kidney injury).
(Choice D) Prednisone is useful in tamping immune activation and is used in managing some forms of autoimmune hemolytic anemia (AIHA).
(Choice E) Splenectomy is useful in many antibody-mediated hematologic disorders (eg, AIHA, idiopathic thrombocytopenia). In PV, the primary problem is myeloproliferation within the bone marrow; splenectomy would not reduce the hematocrit.
Educational objective:
Polycythemia vera is a myeloproliferative disorder characterized by erythrocytosis. It often presents with hypertension, transient vision disturbances, aquagenic pruritus, or thrombosis. Facial plethora and splenomegaly are common on physical examination. Treatment is primarily serial phlebotomy; bone marrow suppressive drugs (eg, hydroxyurea) may sometimes be added if there is a high risk of thrombosis.