Hyperviscosity syndrome is a group of symptoms triggered by an increase in the viscosity of the blood.
Symptoms of high blood viscosity include spontaneous bleeding from mucous membranes, visual disturbances due to retinopathy, and neurologic symptoms ranging from headache and vertigo to seizures and coma.
Hyperviscosity occurs from pathologic changes of either cellular or protein fractions of the blood such as is found in polycythemias, multiple myeloma (particularly IgA and IgG3), leukemia, monoclonal gammopathies such as Waldenström macroglobulinemia, sickle cell anemia, and sepsis.
Those with myeloma will typically display a rouleaux formation on a peripheral smear and a large globulin gap, indicative of a significant paraprotein load.
[5] Plasmapheresis may be used to decrease viscosity in the case of myeloma, whereas leukapheresis or phlebotomy may be employed in a leukemic or polycythemic crisis, respectively.