Multiple choice Waldenström's macroglobulinaemia patients often subsequently develop meningitis duodenal ulcer hyperviscosity syndrome non-Hodgkin's lymphoma multiple myeloma Reveal answer Fill a bubble to check yourself C Correct answer Explanation High levels of serum IgM (a large pentameric protein) make the plasma hyperviscous and this presents with headache, visual disturbances, nose bleeds, malaise or exertional dyspnoea.