polycythemia

Introduction

An increase in red cell mass.

Etiology

• primary increases in erythropoietin
  • renal cell carcinoma
  • hepatocellular carcinoma
  • hemangioblastoma
  • uterine fibroids
  • status post renal transplantation*
• secondary increases in erythropoietin due to hypoxemia
  • chronic pulmonary disease
  • restrictive lung disease
  • right-to-left-cardiac shunt
  • sleep apnea
  • massive obesity
  • high altitude
  • erythrocyte defects
    • hemoglobinopathy, high oxygen affinity
    • 2,3-DPG mutase deficiency
    • methemoglobinemia
    • chronic carbon monoxide poisoning (smoking)
    • Cobalt exposure
• genetic causes (erythropoietin-independent)
  • polycythemia rubra vera
  • activating mutations in erythropoietin receptor
  • Chuvash polycythemia
  • idiopathic familial polycythemia
• relative erythrocytosis (normal red cell mass)
  • hypovolemia/dehydration
    • loss of plasma volume
  • stress erythrocytosis (Gaisbock's syndrome)

* may be erythropoietin-independent

Clinical manifestations

• headache
• dizziness
• paresthesia
• dyspnea
• weakness
• sweating
• weight loss
• hoarseness
• pruritus
  • worse after showering
  • often described as "pins & needles" or prickling sensation
• visual disturbances
• thrombosis
• hyperviscosity
• hypervolemia
• erythromelagia

Laboratory

• serum chemistries
  • serum urea nitrogen
  • serum creatinine
• complete blood count (CBC)
  • hemoglobin > 16.5 (women), 18.5 (men) g/dL (untreated)
  • hematocrit > 50 (women), 55 (men) % (untreated)
• peripheral blood smear
• oxygen saturation to assess hypoxia in etiology
  • pulse oximetry
  • arterial blood gas
• serum erythropoietin
  • low to normal in genetic causes (polycythemia rubra vera)
  • high with hypoxia erythropoietin-producing neoplasm
• JAK2 V617F mutation
• bone marrow biopsy

Complications

• increased incidence of thrombosis due to
  • hyperviscosity, platelet abnormalities
• transformation into myelofibrosis with myeloid metaplasia &/or into acute myeloid leukemia

Management

• phlebotomy to keep hematocrit below 45% men, 42% women
  • best overall survival
  • do not replenish iron stores, mild iron-deficiency inhibits erythropoiesis
• supplement phlebotomy with hydroxyurea if high risk of thrombosis
  • start 15-20 mg/kg/day
• aspirin 75-100 mg/day unless contraindicated
• interferon-alpha (start 3 million units SC if
  • refractory pruritus
  • high-risk women of child-bearing potential
  • refractory to other agents
• anagrelide (start 0.5 mg QID) for thrombocytosis refractory to other treatment
• allopurinol (start 300 mg QD) for symptomatic hyperuricemia
• post renal transplantation erythrocytosis responds to ACE inhibitors

More general terms

• erythrocyte disorder
• hypercoagulability

More specific terms

• polycythemia rubra vera (PRV, PV, erythremia)

Additional terms

• erythrocytosis