White blood cells or leukocytes are the integral part of body's defense system. Sufficient quantity of White Blood Cells (WBCs) is essential to protect you from the pathogenic bacteria, virus, fungi, etc. But this does not mean that increased quantity of WBCs would strengthen the immune system. Even slightly elevated WBC count can prove to be troublesome for you. WBCs are produced in the bone marrow and there exist different types of WBCs. Depending upon which type of WBCs are high in number, the effects of high white blood cell count may vary from person to person.

White Blood Cells
The normal white blood cell count of a person may vary according to the age, sex, overall health, etc. Here is the percentage of various types of WBCs present in blood, when the WBC count is normal.
  • Basophils: 0.4 - 1%
  • Eosinophils: 1 - 3%
  • Lymphocytes: 25 - 35%
  • Monocytes: 4 - 6%
  • Neutrophils: 50 - 70%
Causes of High White Blood Cell Count
Normally, 4300-10,800 white blood cells are present in one cubic millimeter (cmm) of blood. If 10,500 or more leukocytes are found in one micro-liter of blood, then the WBC count is said to be higher than normal. This condition is known as leukocytosis. In case of increased count of WBCs, usually, an increase in one type of white blood cells is noticed. Slightly elevated white blood cell count usually indicates an infection, a problem in the immune system or bone marrow, or it can be a side-effect of a drug. Here is a list of diseases and disorders which can raise the WBC count of an individual.
  • Certain types of leukemia (cancer of blood forming tissues), for example, Acute Lymphocytic Leukemia (ALL) or chronic lymphocytic leukemia that affects the function of the bone marrow.
  • Excessive intake of drugs that contain epinephrine and corticosteroids
  • Measles (vaccination is the best way to prevent measles)
  • Excessive smoking
  • Tuberculosis
  • An immune system disorder
  • Excessive physical and mental stress
  • Rheumatoid arthritis
  • Myelofibrosis, bone marrow disorder wherein bone marrow is replaced by a fibrous tissue.
  • Bacterial and viral infections
  • Severe damage to tissues (for example, in case of burns)
  • Severe allergic reactions
  • Farmer's lung, inflammation of the lungs due to breathing in a harmful substance like dust, fungus, or molds.
  • Kawasaki disease (inflamed blood vessels, a rare condition in children).
  • Excessive cough
  • Chronic bone marrow diseases like myeloproliferative disorder
  • Polycythemia vera, a blood disorder (bone marrow produces excessive red/white blood cells/platelets)
White blood cells comprise only 1% of blood volume in a healthy person. WBCs are present in spleen, liver, and lymph glands along with blood. They are regularly destroyed by the lymphatic system after their use. These cells surround and attack the bacteria and viruses and finally destroy them. WBCs can create antibodies to fight infections. But high WBC count leads to increased risk of cardiovascular mortality and a very low WBC count increases the risk of sepsis. You should consult your physician if you see abnormal blood count in the test results.

Some of the above diseases may exhibit symptoms like breathing difficulty, dizziness, fullness in the left upper abdomen due to enlarged spleen, easy bleeding, fatigue, frequent infections, etc. Unhealthy food habits, wrong sleeping habits, lack of essential nutrients in diet, pollution and stress can be easily avoided with the help of dietary and lifestyle changes. Regular exercise and healthy food keeps you fit and active. Good eating and sleeping habits promote healthy levels of hormones, blood components, vitamins and electrolytes. Regular blood tests help measure and monitor the blood cell count.

Pregnant women and elderly people may notice slightly elevated WBC count. It is considered normal. During pregnancy, women need extra WBCs to protect themselves and protect the fetus from infections. Similarly an elderly person's body may need extra WBCs to strengthen the immune system. Routine blood tests help detect a problem at an earlier stage. Prompt diagnosis and correct treatment help bring back the WBC count to the normal levels.