What is the difference between hyperviscosity and hypercoagulable states?

Hyperviscosity vs. Hypercoagulable States: Key Differences

Hyperviscosity and hypercoagulable states are distinct clinical conditions with different pathophysiological mechanisms, though both can increase the risk of thrombosis and impair blood flow.

Hyperviscosity Syndrome

Definition and Pathophysiology

• Hyperviscosity refers to increased resistance to blood flow due to altered physical properties of blood components, resulting in impaired microcirculation 1, 2
• It occurs when blood becomes abnormally thick and flows poorly through the microvasculature 3

Causes of Hyperviscosity

• Increased cellular components:

  • Secondary erythrocytosis (physiological increase in red cell mass due to hypoxemia) 1
  • Polycythemia (neoplastic proliferation of hematopoietic cells) 1
  • Extreme leukocytosis (increased white blood cells) 2, 4

• Increased plasma proteins:

  • Elevated immunoglobulins (monoclonal gammopathies like multiple myeloma) 1
  • Hyperfibrinogenemia and inflammatory states 5
  • Dysglobulinemias (Fahey's syndrome) 5

Clinical Manifestations

• Headache, faintness, dizziness, fatigue, tinnitus, blurred vision 1
• Paresthesia of fingers, toes, and lips 1
• Muscle pain and weakness 1
• Mucosal hemorrhage and retinal hemorrhages 2
• Neurologic symptoms (seizures, vertigo, diplopia) 1
• Cardiac manifestations (heart failure) 1

Treatment

• First-line therapy: Rehydration with oral fluids or intravenous normal saline 1
• Plasma exchange: For symptomatic hyperviscosity, especially with neurologic or hemorrhagic manifestations 1, 3
• Phlebotomy: Reserved for special cases with persistent symptoms after adequate hydration or evidence of end-organ damage 1
• Treatment of underlying cause: Chemotherapy for malignancies, correction of iron deficiency 1

Hypercoagulable States

Definition and Pathophysiology

• Hypercoagulability refers to an abnormal tendency toward thrombosis due to alterations in the coagulation cascade or platelet function 1, 6
• It involves an imbalance between procoagulant and anticoagulant pathways 1

Types and Causes

• Inherited hypercoagulable states:

  • Factor V Leiden mutation 1, 6
  • Prothrombin 20210 mutation 1
  • Protein C deficiency 1, 6
  • Protein S deficiency 1, 6
  • Antithrombin III deficiency 1, 6
  • Congenital hyperhomocysteinemia 6

• Acquired hypercoagulable states:

  • Antiphospholipid antibody syndrome 1, 6
  • Malignancy 6
  • Pregnancy and postpartum state 6
  • Myeloproliferative disorders 6
  • Inflammatory conditions 1
  • Sepsis/critical illness 1

Clinical Manifestations

• Venous thromboembolism (deep vein thrombosis, pulmonary embolism) 6
• Arterial thrombosis (stroke, myocardial infarction) 6
• Recurrent pregnancy loss 1
• Thrombosis in unusual sites (cerebral sinuses, portal vein) 1

Treatment

• Anticoagulation therapy:
  • Oral anticoagulants (warfarin) 6
  • Injectable anticoagulants (heparins) 6
  • Direct oral anticoagulants (DOACs) 6
• Antiplatelet therapy: For arterial thrombosis, especially with hyperhomocysteinemia 6
• Treatment of underlying cause: When applicable 6

Key Differences

• Fundamental mechanism:

  • Hyperviscosity: Physical property change of blood (thickness/flow) 5, 2
  • Hypercoagulability: Biochemical imbalance in coagulation factors/pathways 1

• Laboratory assessment:

  • Hyperviscosity: Measured by viscometers, hematocrit, protein levels 5
  • Hypercoagulability: Assessed by coagulation tests, genetic testing, antibody assays 1

• Primary treatment approach:

  • Hyperviscosity: Hydration, plasma exchange, phlebotomy 1, 3
  • Hypercoagulability: Anticoagulation, antiplatelet therapy 6

• Predominant clinical outcomes:

  • Hyperviscosity: Both bleeding and thrombosis can occur 1
  • Hypercoagulability: Primarily thrombotic complications 6

• Paradoxical effects:

  • In hyperviscosity, patients can experience both bleeding and thrombotic complications simultaneously 1
  • In hypercoagulability, the primary concern is thrombosis formation 6