The severity of clinical symptoms is directly related to the increased levels of serum viscosity, with progressively more severe symptoms occurring as the individual patient’s serum viscosity increases. An increase in circulating proteins can also affect platelet aggregation and cause prolonged bleeding time. This increase in viscosity causes sluggish blood flow, relative decreased microvascular circulation, and hypoperfusion of tissues. This includes RBC, WBC, platelets, or serum proteins. An increase in blood viscosity can be caused either by a deformity of the shape of red blood cells (RBCs) which causes RBC aggregation and decreased blood flow or by any pathological elevation of the components of blood. HVS is the pathological condition in which blood is 'thicker' than normal and therefore flow is reduced. Viscous fluids are thicker and travel more slowly. When fluid has low viscosity, it travels quickly and without much difficulty. ReferencesĬhandler WL and Schmer G, Evaluation of a new dynamic viscometer for measuring the viscosity of whole blood and plasma, Clin Chem (1986) 32:505.Viscosity is formally defined as the measurement of the internal resistance of a fluid to flow but can simply be thought of as the 'thickness' or 'stickiness' of a fluid. Hyperviscosity syndrome can also occur in multiple myeloma patients, and, rarely, in patients with rheumatoid factors and other aggregating proteins.

The most common cause of serum hyperviscosity is the presence of large concentrations of IgM monoclonal proteins, and Waldenstrom's macroglobulinemia accounts for 80% to 90% of symptomatic hyperviscosity cases. Although viscosities >1.6 are abnormal, hyperviscosity syndromes are rarely present unless the relative viscosity is >4.0 (approximately). Results are reported as a relative viscosity to water, where normal serum and plasma have a relative viscosity of up to 1.6. Serum, plasma or whole blood viscosity measurements can be useful in patients with hyperviscosity syndromes due to multiple myeloma or Waldenstrom's macroglobulinemia. Viscosity is the property of fluids to resist flow. Lab Name Viscosity, Serum Lab Code SRVISG Epic Ordering

Blood viscosity test