Patients with very high white counts (>75-100 x 109/L) should be assessed for symptoms of leukostasis. This is a hyperviscosity syndrome which may present with a myriad of symptoms such as respiratory symptoms (perhaps mimicking pulmonary embolism) and neurological/visual symptoms (perhaps mimicking stroke), and more rarely myocardial ischaemia, bowel ischaemia, ischaemic limb, or acute kidney injury. Emergency treatments for those with very high counts and/or clinical symptoms include chemotherapy and leukopharesis (removal of white cells from blood).