Patient 9560 is an 86 year old male with Waldenström’s macroglobulinaemia (WM), which is being treated with Ibrutinib. WM is a rare indolent (slow-growing) non-Hodgkin lymphoma, a cancer of the lymphatic system. WM cells produce large amounts of immunoglobulin M (IgM). Overproduction of IgM causes the blood to become too thick, thus impairing blood flow, especially through small blood vessels. Consequently, the patient was prescribed Amlodipine, a calcium channel blocker used to widen to blood vessels to lower blood pressure. This complication of thick blood is called hyperviscosity. It can cause problems such as poor circulation to the brain and other organs, which can lead to symptoms like those from a stroke. It can also affect the amount