Bone marrow makes blood cells, including red blood cells, white blood cells, and platelets. In some older persons, there is a problem with the bone marrow in which the marrow cannot make new blood cells effectively (myelodysplastic syndromes). These persons get low numbers of red blood cells (anemia), white blood cells (neutropenia), or platelets (thrombocytopenia). Low numbers of red blood cells and platelets require frequent transfusions to prevent tiredness, shortness of breath, and bleeding. Low numbers of white blood cells lead to infections and a frequent need for antibiotics.