Bone marrow is removed under anesthetic using a long hollow needle from the donor for bone marrow transplants. The needle is usually inserted into the pelvic bone and does cause pain and the donor is sore for several days afterwards. That alone might keep it impractical to remove bone marrow, but the bone marrow is replaced by the body in 4-6 weeks, and with thal it would only increase the production of new marrow. As sharmin has stated, it is best to suppress overproduction of bone marrow by keeping the hemoglobin level up. In intermedia if anything that can be done to increase Hb production to a level that will minimize overproduction in the marrow, such as using hemoglobin enhancing drugs, or possibly natural substances such as wheatgrass or aloe, it is advised over transfusions.