What does hyperviscosity or blood settling indicate?

Blood Bland Settlement Indicates Hyperviscosity Syndrome

Blood bland settlement (hyperviscosity) indicates increased resistance to blood flow due to altered physical properties of blood components, resulting in impaired microcirculation that can lead to serious complications requiring immediate intervention. 1

Causes of Hyperviscosity

• Monoclonal Gammopathies: The most common cause is increased concentrations of immunoglobulins, particularly in Waldenström macroglobulinemia (WM) where IgM is a pentamer and frequent cause of hyperviscosity (10-30% of WM cases) 2
• Polycythemia: Secondary erythrocytosis with elevated red blood cell mass can cause whole-blood hyperviscosity 2
• Extreme Leukocytosis: Increased white blood cell counts can contribute to hyperviscosity 3
• Cryoglobulinemia: Presence of cryoglobulins may affect IgM levels and contribute to hyperviscosity 2

Clinical Manifestations

Neurological Symptoms

• Headache, dizziness, vertigo, confusion, and altered mental status 1, 3
• Paresthesia of fingers, toes, and lips 2
• Seizures and diplopia in severe cases 1

Ocular Manifestations

• Blurred vision or visual loss 2
• Retinal venous engorgement ("sausaging") - a reliable sign of clinically relevant hyperviscosity 2
• Retinal hemorrhages and central retinal vein occlusion in severe cases 4

Other Symptoms

• Epistaxis (nose bleeds) and bleeding diathesis 2, 3
• Fatigue and weakness 2, 1
• Tinnitus and hearing impairment in rare cases 4

Diagnostic Approach

• Serum Viscosity Measurement: Though it may not correlate well with clinical severity of the syndrome 2
• Fundoscopic Examination: More reliable than serum viscosity for clinically relevant hyperviscosity, looking for venous engorgement 2
• Laboratory Tests:
  • Complete blood count with differential to assess for polycythemia or leukocytosis 2
  • Serum protein electrophoresis and immunofixation to identify and quantify monoclonal proteins 2
  • Testing for cold agglutinins and cryoglobulins 2
  • Bone marrow biopsy in suspected WM to document clonal lymphoplasmacytic cell population 2

Management

Immediate Interventions

• Rehydration: Oral fluids or intravenous normal saline as first-line therapy for hyperviscosity 2, 1
• Plasma Exchange/Plasmapheresis: For symptomatic hyperviscosity, especially with neurologic or hemorrhagic manifestations 1, 5
  • Removes 80% of IgM protein and is effective in relieving symptoms of hyperviscosity 2
  • Indicated for treatment of symptomatic hyperviscosity, usually as supplement to conventional systemic therapies 2

Special Considerations for Erythrocytosis

• Phlebotomy: Reserved for special cases with persistent symptoms after adequate hydration or evidence of end-organ damage 2, 1
  • Recommended when hemoglobin exceeds 20 g/dL and hematocrit exceeds 65% with symptoms of hyperviscosity 6
  • Should not be performed in presence of dehydration or anemia 6
  • Involves removing one unit of blood with equal volume fluid replacement 6

Long-term Management

• Treatment of underlying condition:
  • For WM: Alkylating agents, nucleoside analogs, rituximab, thalidomide, bortezomib, or ibrutinib 2
  • For polycythemia: Maintaining appropriate hematocrit levels 6

Important Considerations and Pitfalls

• Serum Viscosity vs. Clinical Symptoms: Serum viscosity does not always correlate well with clinical severity; clinical symptoms and fundoscopic findings are more reliable indicators for intervention 2, 1
• Iron Deficiency Risk: Repeated routine phlebotomies are not recommended due to risk of iron depletion, which can reduce oxygen-carrying capacity and increase stroke risk 6
• Laboratory Challenges: The presence of cold agglutinins or cryoglobulins may affect determination of IgM levels, leading to falsely low readings 2
• Monitoring Requirements: Regular assessment of symptoms and laboratory parameters is essential during treatment 6
• Emergency Recognition: Hyperviscosity syndrome with neurological or visual symptoms represents a medical emergency requiring immediate intervention 4