Leucocytosis: What it is and main causes


Leukocytosis is a condition in which the number of leukocytes, i.e. white blood cells, is above normal, which in adults may go up to 11,000 per mm³.

The function of these cells is to fight infections and aid in working of the immune system. Their increase therefore is an indication of a problem and that the body is trying to fight a disease, and this can be the first sign of an infection.

Leukocytosis and skin infections

Types of leukocytosis


Leukocytes consists of various types of white blood cells and their increase usually occur in only one of these type of cells. The 5 main types of leucocytosis include:

  • Neutrophilia: This is the increase of neutrophils, which usually happens due to excessive stress, excessive physical exercise, diabetes or attack by some infections.
  • Lymphocytosis: Is the increase in the number of lymphocytes and is one of the most common types, arising in cases of recurrent infections such as flu or allergy.
  • Monocytosis: This is the increase in the number of monocytes and is a rarer change, which may indicate chronic infections such as tuberculosis, colitis or even leukaemia.
  • Eosinophilia: This is an increase in the number of eosinophils and is usually and more common during allergies or infections by parasites or fungi.
  • Basophilia: This is an increase in basophils and is a very rare change that can indicate problems such as asthma, sinusitis, anaemia, colitis or even leukemia.

To evaluate the amount of these components in the blood, the doctor will perform a leukogram, which is included in the blood count. The usual values of leukocytes in blood varies depending on the age of the individual.

Main causes of leukocytosis

The number of leukocytes may be altered by any problem affecting the body but there are more specific causes depending in the type of leukocytes that have been altered. The most common causes of leucocytosis include:

1. Infections

Infections in the body either by viruses, fungi ir bacteria always cause an alteration in some of the main types of leukocytes and it is therefore a major cause of leucocytosis.

bacterial infections 101 s1 what is bacteria

There are many types of infections and for this reason the doctor needs to evaluate the symptoms that are experienced then perform specific tests so as to identify the specific cause then prescribe the appropriate treatment. If the cause becomes difficult to identify, some physicians may choose to begin treatment using an antibiotic, because most infections are caused by bacteria. He will then asses the if the symptoms are improving or the amount of leukocytes is regulated.

2. Allergies

Allergies such as asthma, sinusitis or rhinitis may also cause an increase in the number of leukocytes, especially the eosinophil and basophil type.

In such cases, the doctor will perform an allergy test as as to understand the cause of the allergy especial if no symptoms are presented to help in the diagnosis.

3. Use of medicines

Some drugs such as Lithium or Heparin are known to cause changes in the blood cells, especially in the number of leukocytes, hence causing leucocytosis. Therefore, whenever there is a change in the blood test, it is important to inform the doctor of the type of medicines in use.

If necessary, the doctor may adjust the dose of the drug in use or switch to another medicine that has the same effect, but does not reset in changes in the blood cells.

4. Chronic inflammations

Chronic or autoimmune diseases such as colitis, rheumatoid arthritis or irritable bowel syndrome can result in constant inflammation, which may cause the body to produce more leukocytes to fight what has been altered in the body.

5. Cancer

Although it is rare, an increase in number of leukocytes may also be a sign of the development of cancer. The most common type of cancer that causes leucocytosis is leukaemia. However, other types of cancers such as lung cancer can also result in changes in the amount of leukocytes.

Whenever you experience suspicions of cancer, the doctor may perform other tests to confirm the diagnosis.

What can cause leukocytosis in pregnancy?

Leukocytosis is a relatively normal change in pregnancy, and the number of leukocytes may increase throughout pregnancy to values up to 14,000 per mm³.

Symptoms of Leukemia in Pictures Rashes and Bruises 732x549 thumbnail 1 732x549 1

In addition, leukocytes also tend to increase after childbirth due to stress caused by the body. Thus, the woman who was pregnant may have leucocytosis even after pregnancy for a few weeks.

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Cornelius Arthur
I am an English language and literature teacher. I have worked in many cities of the world. I am currently producing content at upwork as a freelance. I find and produce the right content by doing good research.


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