Treatment for hyperviscosity syndrome may vary based on the underlying cause. Hyperviscosity syndrome worsens dehydration, so your provider may prescribe intravenous (IV) hydration. In severe cases, healthcare providers may use: Partial exchange transfusions, where they remove a small amount of blood and replace it with saline solution. Plasmapheresis, where they remove and replace a small amount of plasma, the clear liquid part of your blood.