A low white-blood-cell count can be caused by many different diseases. A decrease of white blood cells, called leukocytes, means a decrease in your ability to fight infections. There are different types of white blood cells and you might have a decrease in just one type. A low white-blood-cell count is called leukopenia and it can be caused by viral infections, congenital disorders, cancer, certain drugs and autoimmune diseases.
Aplastic Anemia
Aplastic anemia is a disease where damage to your bone marrow inhibits production of new blood cells. Symptoms of aplastic anemia include fatigue, pale skin, heart murmur, rapid pulse, dizziness, headache, skin rash, persistent infections, bruising and prolonged bleeding from wounds. It can be caused by radiation and chemotherapy, some drugs, an autoimmune disorder, toxic chemicals or a viral infection. Treatment can include transfusions of whole blood, red blood cells or platelets, a bone marrow transplant, immunosuppressants, antibiotics and antivirals or bone-marrow stimulants.
HIV/AIDS
The human immunodeficiency virus (HIV) causes the development of acquired immunodeficiency syndrome (AIDS). HIV hinders your ability to fight other conditions and diseases. HIV puts you at a higher risk of some types of cancer and infections. Symptoms that can develop over a period of 10 years or more, may begin with fever, sore throat, headache, rash and swollen glands and progress to weight loss, diarrhea, cough, fever and shortness of breath. In later stages, infections can include additional symptoms. While there is no cure, a variety of treatments exist.
Hyperthyroidism
Hyperthyroidism is a disease where too much thyroxine, a hormone that speeds your metabolism, is produced by your thyroid gland. Symptoms include sudden weight loss, increased appetite, sweating, rapid heartbeat, anxiety, fatigue, sleeping problems, bowel changes and sensitivity to heat. Hyperthyroidism can be caused by Graves' disease, an autoimmune disorder, thyroiditis, an inflammation of the thyroid gland or hyperfunctioning thyroid nodules. Treatment includes anti-thyroid medications such as propylthiouracil and methimazole, radioactive iodine, beta blockers or surgery.
Leukemia
Leukemia is a cancer that affects your lymphatic system and bone marrow. Your bone marrow generates large quantities of white blood cells that do not function normally. Symptoms include fever and chills, fatigue, weakness, persistent infections, swollen lymph nodes, loss of appetite and weight loss, bruising easily, shortness of breath, excessive sweating, bone pain and petechiae. The disease can be acute, progressing rapidly, or chronic, where symptoms might not be present immediately. Treatment include chemotherapy, immunotherapy, radiation, bone marrow transplant and other drug therapies.
Autoimmune Disorders
A low white blood count can be the result of other autoimmune diseases, such as lupus and rheumatoid arthritis. Lupus is a chronic inflammatory condition that can affect your joints, kidneys, blood cells, skin, heart and lungs. Rheumatoid arthritis is a inflammatory condition that affects your joints, causing swelling, pain and over time, deformities.
Congenital Disorders
Congenital disorders include Kostmann's syndrome and myelokathexis. Both diseases affect the neutrophils, which according to Merck, make up between 45 percent and 75 percent of your white blood cells. With Kostmann's syndrome, your production of these cells is low, and in myelokathexis, the neutrophils fail to enter the bloodstream. Both result in neutropenia, which is a decrease of white blood cells and increases the risk of infections and the chances of developing leukemia.
