White blood cells (leukocytes) represent a large population of different cells building almost the entire human immune system. There are various subtypes of leukocytes, some of which are responsible for so-called innate immunity (neutrophil granulocytes, macrophages) while the others are components of our acquired immunity.
Although their role is protective, leukocytes can sometimes have a harmful effect on the body as mediators in autoimmune diseases, inflammatory processes, and hematological disorders.
What Is A Normal Leukocyte Count?
The total leukocyte count is the number of white blood cells (including all subtypes) per unit of blood volume. The normal value is in the range of 4000-10000 per micro liter of blood. Values higher than 10000 are labeled as leukocytosis, while values lower than 4000 represent leucopenia. Whenever there is an abnormal leukocyte count, a leukocyte formula should be ordered to examine the count of particular subtypes of white blood cells. Knowing exactly which subtype is out of the normal range can help with making the right diagnosis.
Causes Af A High Leukocyte Count
Infection is the most common cause of an increased leukocyte count. Both bacterial and viral, and local or systemic infections can increase the number of circulating leukocytes. In the case of bacterial infection, the neutrophil granulocyte count is usually higher than normal, while viral infections are often characterized by a higher lymphocyte count. Parasitic infections such as pin worms can cause an increased eosinophil granulocyte count. For some asymptomatic infections, a high leukocyte count can be the only sign of infection.
Allergic disorders can sometimes manifest with a high leukocyte count, especially the eosinophil subtype. Further tests are then needed in order to prove the cause of the allergy.
The most common tumors of blood cells are leukemia and lymphoma. These are serious diseases that often produce a disturbed white blood cell count. If the count of white blood cells is abnormally increased, additional examinations such as a bone marrow biopsy are necessary to investigate the possibility of leukemia. Besides blood cancer, tumors in general can increase the leukocyte count as the immune system is responsible for fighting against tumor cells.
Autoimmune disorders are a large and growing group of immune system disorders in which person's immune system attacks their own tissues and organs. The lymphocyte count can be increased during flare-ups of these diseases, although that is not a necessary finding.
As infections are the most common causes of an increased leukocyte count, there is usually no reason to worry, but every case should be referred to a doctor along with other symptoms for further investigation.
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