Hyperviscosity Syndrome

Aka: Hyperviscosity Syndrome, Leukostasis, Hyperleukocytosis of Malignancy

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II. Causes

  1. Oncology related cases
    1. Acute Myelogenous Leukemia (AML), accounts for 20% of cases
    2. Chronic Myelogenous Leukemia (CML) if in Blast Crisis, evolution to AML
    3. Multiple Myeloma
    4. Waldenstrom's Macroglobulinemia (10-30% of cases)
  2. Other causes
    1. Polycythemia Vera
    2. Sickle Cell Anemia
    3. Sepsis

III. Pathophysiology

  1. Overall increased serum viscosity results in microvascular hypoperfusion
    1. Increased viscosity and sludging of blood cells in the microvasculature
    2. End result is end organ decreased perfusion (esp. lung and CNS)
  2. Dramatically increased cell counts
    1. Red Blood Cells: Polycythemia Rubra Vera
    2. White Blood Cells: Hyperleukocytosis (with White Blood Cells >100,000)
      1. Especially seen in acute leukemic Blast Crisis (AML or CML)
  3. Increased circulating serum Immunoglobulins
    1. Immunoglobulins coat Red Blood Cells
    2. Results in cell aggregation in the microvasculature
  4. Primitive leukemic cells invade microvascular endothelium
    1. Results in intraparenchymal Hemorrhages

IV. Signs

  1. Spontaneous bleeding from mucous membranes
  2. Fever in 80% of patients
  3. Pulmonary symptoms in 30% of cases
    1. Dyspnea
    2. Hypoxia
    3. Pulmonary Infiltrates (CXR) may be seen
  4. Vision change
    1. Hemorrhagic Retinal veins (appear as sausages, pathognomonic)
  5. Neurologic symptoms (e.g. Transient Ischemic Attack) in 40% of cases
    1. Headache
    2. Ataxia
    3. Vertigo
    4. Seizures
    5. Altered Level of Consciousness or confusion
    6. Peripheral Neuropathy

V. Labs

  1. Complete Blood Count
    1. Marked increased in a cell line
      1. White Blood Cells markedly increased or Hyperleukocytosis (e.g. Acute Myelogenous Leukemia)
        1. Hyperleukocytosis with White Blood Cell Count >100,000 (>50,000 in some criteria)
      2. Red Blood Cells markedly increased (e.g. Polycythemia Rubra Vera)
    2. Other cell lines may be elevated
      1. Platelet Count falsely elevated
  2. Peripheral Blood Smear
  3. Serum Electrolytes with Renal Function panel
    1. Hyperkalemia may be present
  4. Urinalysis
  5. Coagulation Panel (e.g. INR/PT, PTT)
  6. Serum viscosity: >4-5 centipoise (cP)
    1. Serum viscosity is normally near 1.4 cP
    2. Water viscosity is 1 cP

VI. Imaging

  1. Chest XRay or CT Chest
    1. Widespread Pulmonary Infiltrates may be seen

VII. Differential Diagnosis

  1. Asymptomatic Hyperleukocytosis or Leukemoid Reaction
    1. Elevated White Blood Cell Count >50,000 to 100,000
    2. Asymptomatic (but high risk for Leukostasis)
    3. Urgent hematology Consultation (but typically does not require hospitalization)

VIII. Management

  1. Oncologic Emergency
    1. Immediate Consultation with hematology and oncology
    2. Admit to Intensive Care
  2. Temporize
    1. Aggressive Intravenous Fluids
    2. Respiratory support (including Endotracheal Intubation if needed)
    3. Obtain Central Line access if Apheresis is planned
    4. Empiric Antibiotics
      1. Fever is present in 80% of patients who also have severe Leukocytosis on Chemotherapy
      2. Antibiotics are indicated to cover the differential diagnosis in this high risk group
    5. Reduce Hyperuricemia risk
      1. Rasburicase
    6. Avoid all treatments that increase blood viscosity and exacerbate Leukostasis
      1. Diuretics
      2. Blood Transfusions
  3. Decrease cellular load (cytoreduction)
    1. Multiple Myeloma (or other Monoclonal Gammopathy)
      1. Plasmapheresis
    2. Polycythemia
      1. Phlebotomy
    3. Leukostasis
      1. Induction Chemotherapy (first-line, only measure associated with reduced mortality)
      2. Leukapheresis
      3. Hydroxyurea
        1. May be indicated in asymptomatic patients
        2. Dosing 50-100 mg/kg/day

IX. Complications

  1. Intracranial Hemorrhage
    1. Risk increases for first week after treatment
  2. Myocardial Ischemia
  3. Acute Limb Ischemia
  4. Acute Kidney Injury
  5. Disseminated Intravascular Coagulation or DIC (40% of cases)
  6. Tumor Lysis Syndrome
    1. Prophylaxis with Intravenous Fluids and Allopurinol prior to Chemotherapy

X. Prognosis

  1. Untreated mortality approaches 40% in first week

XI. References

  1. Aurora and Herbert in Herbert (2013) EM:Rap 13(10): 1-4
  2. Bierowski and Nyalakonda (2025) Crit Dec Emerg Med 39(6): 4-21
  3. Long, Long and Koyfman (2020) Crit Dec Emerg Med 34(11): 17-24
  4. Higdon (2006) Am Fam Physician 74:1873-80 [PubMed]
  5. Higdon (2018) Am Fam Physician 97(11):741-8 [PubMed]
  6. Zuckerman (2012) Blood 120(10): 1993-2002 [PubMed]

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