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polycythemia

An increase in red cell mass. Etiology: 1) primary increases in erythropoietin a) renal cell carcinoma b) hepatocellular carcinoma c) hemangioblastoma d) uterine fibroids e) status post renal transplantation* 2) secondary increases in erythropoietin due to hypoxemia a) chronic pulmonary disease b) restrictive lung disease c) right-to-left-cardiac shunt d) sleep apnea e) massive obesity f) high altitude g) erythrocyte defects - hemoglobinopathy, high oxygen affinity - 2,3-DPG mutase deficiency - methemoglobinemia - chronic carbon monoxide poisoning (smoking) - Cobalt exposure 3) genetic causes (erythropoietin-independent) a) polycythemia rubra vera b) activating mutations in erythropoietin receptor c) Chuvash polycythemia d) idiopathic familial polycythemia 4) relative erythrocytosis (normal red cell mass) a) hypovolemia/dehydration - loss of plasma volume b) stress erythrocytosis (Gaisbock's syndrome) * may be erythropoietin-independent Clinical manifestations: 1) headache 2) dizziness 3) paresthesia 4) dyspnea 5) weakness 6) sweating 7) weight loss 8) hoarseness 9) pruritus a) worse after showering b) often described as "pins & needles" or prickling sensation 10) visual disturbances 11) thrombosis 12) hyperviscosity 13) hypervolemia 14) erythromelagia Laboratory: 1) serum chemistries a) serum urea nitrogen b) serum creatinine 2) complete blood count (CBC) a) hemoglobin > 16.5 (women), 18.5 (men) g/dL (untreated) b) hematocrit > 50 (women), 55 (men) % (untreated) 3) peripheral blood smear 4) oxygen saturation to assess hypoxia in etiology a) pulse oximetry b) arterial blood gas 5) serum erythropoietin a) low to normal in genetic causes (polycythemia rubra vera) b) high with hypoxia erythropoietin-producing neoplasm 6) JAK2 V617F mutation 7) bone marrow biopsy Complications: 1) increased incidence of thrombosis due to - hyperviscosity, platelet abnormalities 2) transformation into myelofibrosis with myeloid metaplasia &/or into acute myeloid leukemia Management: 1) phlebotomy to keep hematocrit below 45% men, 42% women - best overall survival - do not replenish iron stores, mild iron-deficiency inhibits erythropoiesis 2) supplement phlebotomy with hydroxyurea if high risk of thrombosis - start 15-20 mg/kg/day 3) aspirin 75-100 mg/day unless contraindicated 4) interferon-alpha (start 3 million units SC if a) refractory pruritus b) high-risk women of child-bearing potential c) refractory to other agents 5) anagrelide (start 0.5 mg QID) for thrombocytosis refractory to other treatment 6) allopurinol (start 300 mg QD) for symptomatic hyperuricemia 7) post renal transplantation erythrocytosis responds to ACE inhibitors

Related

erythrocytosis

Specific

polycythemia rubra vera (PRV, PV, erythremia)

General

erythrocyte disorder hypercoagulability

References

  1. Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 600-602
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, American College of Physicians, Philadelphia 1998, 2009
  3. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 206-207
  4. UpToDate Online version 15.1
  5. Spivak JL. How I treat polycythemia vera. Blood. 2019;134:341-352. PMID: 31151982