Polycythemia is a topic covered in the 5-Minute Emergency Consult.

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Basics

Description

  • Increase in hemoglobin (Hgb) above the normal range:
    • Men: Hgb >17.5 g/dL, hematocrit (Hct) >52%
    • Women: Hgb >16 g/dL, Hct >48%
  • Symptoms are related to blood viscosity, which increases exponentially at Hct >60%.

Etiology

  • Relative (apparent) polycythemia:
    • Resulting from decrease in plasma volume
    • Acute: Dehydration
    • Chronic: Gaisbock syndrome (stress polycythemia): Obese, hypertensive, middle-aged smokers
  • Primary erythrocytosis:
    • Polycythemia vera (PV): A stem cell disorder characterized by panhyperplasia of all bone marrow elements leading to increased production of RBCs, WBCs, and platelets. Erythrocytosis is the most prominent feature:
      • Mutation in the tyrosine kinase (JAK2), which acts in signaling pathways of the EPO-receptor, rendering those cells hypersensitive to erythropoietin
      • Median age 60, 5% <40, peak in 70s
      • Higher in Ashkenazi Jews and lower in Asians and African Americans.
      • May progress to myelofibrosis or acute leukemia
  • Secondary polycythemia:
    • Central hypoxia increasing erythropoietin:
      • Chronic pulmonary disease
      • Sleep apnea (5–10% have high Hgb)
      • Obesity hypoventilation syndrome (Pickwickian syndrome)
      • Congenital heart disease (right-to-left shunt)
      • High altitude (chronic)
      • Smoker's erythrocytosis
      • Carbon monoxide poisoning (chronic)
      • Chronic methemoglobinemia
    • Renal-mediated causes of increased erythropoietin production:
      • Renal cell carcinoma
      • Renal artery atherosclerotic narrowing
      • Focal glomerulonephritis
      • Postrenal transplant with or without rejection
      • Chronic hydronephrosis
      • Polycystic kidney disease and renal cysts
    • Inappropriate autonomous erythropoietin production:
      • Hepatomas
      • Cerebellar hemangioblastoma
      • Wilms tumor
      • Parathyroid carcinoma and adenoma
      • Ovarian tumors
      • Adrenal adenomas and carcinomas (pheochromocytoma, Cushing)
      • Uterine leiomyomata
    • Blood doping:
      • Recombinant erythropoietin abuse
      • Autologous transfusions
    • Drug abuse:
      • Chronic cocaine abuse
      • Androgenic steroids
  • Genetic disorders with polycythemia:
    • High-affinity Hgb variants
    • Bisphosphoglycerate deficiency
    • von Hippel–Lindau syndrome
    • Chuvash polycythemia
    • Erythropoietin-receptor mutations
    • Congenital methemoglobinemia
  • Infections:
    • Viral hepatitis, AIDS

Diagnostic Criteria for Polycythemia Vera
  • Major criteria:
    • Hgb >18.5 g/dL in men, >16.5 g/dL in women
    • Presence of JAK2 mutation by polymerase chain reaction (PCR) – clinches the dx
    • Oxygen saturation >92% and no other cause for secondary erythrocytosis
  • Minor criteria:
    • Low serum erythropoietin level
    • Bone marrow aspirate and biopsy revealing panhyperplasia
  • Adjuncts to diagnosis:
    • Platelets >400,000/mm3
    • ANC >10,000 (WBC >12,000/mm3)
    • Splenomegaly on exam or by CT
    • Leukocyte alkaline phosphatase elevation
    • B12 >900 pg/mL; unbound vitamin B12-binding capacity >2,200 pg/mL

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Citation

* When formatting your citation, note that all book, journal, and database titles should be italicized* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Polycythemia ID - 307193 Y1 - 2016 PB - 5-Minute Emergency Consult UR - https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307193/all/Polycythemia ER -