MayoClinic.com defines leukemia as a cancer "of the body's blood-forming tissues, including the bone marrow and the lymphatic system." They explain further that the disease causes white blood cells to reproduce uncontrollably. These immature white cells are often referred to as blasts. Most of the symptoms of leukemia are directly or indirectly related the the excessive production of these cells.
Anemia
Leukemia can cause anemia because the bone marrow becomes so packed with white cells that it is unable to make red cells. The Merck Manual explains that "this interference with normal bone marrow cell function can lead to inadequate numbers of red blood cells," which causes anemia. Patients with anemia get profoundly fatigued and out of breath by simple activities.
Anemia can be diagnosed by doing a complete blood count, commonly called a CBC.
Achy Bones
According to the Children's Hospital of Philadelphia, the bone marrow in patients with leukemia can be so packed with blasts that the bones themselves start to ache. This pain is unique, as it does not feel at all like muscle strains or other aches and pains one gets from working out.
Bruises
Platelets are a type of cell involved in blood clotting. Like red blood cells, platelets are made in the marrow of bones. As explained by Merck, when the marrow is packed with blasts, platelet formation is impossible.
Patients with low platelet counts often have inexplicable bruising caused by blood pooling under the skin. The Leukemia and Lymphoma Society notes that patients may bleed excessively when injured. This symptom would not occur if platelet counts were normal.
Abdominal Pain
The Children's Hospital of Philadelphia says that blasts often pool in the abdominal cavity near the spleen, kidneys and liver, where they cause abdominal pain. The Leukemia and Lymphoma Society explains that in some instances, the spleen can be so enlarged that the best solution is to remove it surgically.
Infections
Even though their white cell count is high, MayoClinic.com notes that leukemia patients often get sick frequently, acquire infections easily and develop fevers with chills. They are prone to these unrelated diseases because their white cells are immature and cannot launch an effective immune response.
