What is hyperviscosity?

A symptom of Waldenstrom’s macroglobulinaemia, where the blood becomes thicker (more viscous) and stickier. This is caused by increased amounts of abnormal B-cells which overproduce a type of antibody called IgM. This overproduction of IgM is what makes the blood thicker. Hyperviscosity can cause headaches, blurred vision, nosebleeds, dizziness and shortness of breath, amongst other symptoms.