What Causes a Decrease in White Blood Cells?

By Max. D Gray. Updated: January 24, 2017
What Causes a Decrease in White Blood Cells?

White blood cells or leucocytes play a crucial role in our body. They are responsible for defending the body from infections and foreign bodies that could damage our health. As a result, if there is a decline in your white blood cell count, an in-depth medical evaluation is necessary to identify the source of the problem.

In this oneHOWTO article, we'll explain what causes a decrease in white blood cells, going through the main reasons why your leucocyte count may have dropped.

You may also be interested in: What Foods Increase White Blood Cells

What are white blood cells or leucocytes?

Although we usually refer to this group of cells with the catch-all terms white blood cells or leucocytes, they actually consist of different types, each of which is responsible for various functions in our body's defense mechanism.

Identifying what they do will prove important when it comes to determining which white blood cells have decreased exactly and the possible causes and consequences of this decline.

  • Lymphocytes: produce antibodies and destroy abnormal cells.
  • Monocytes: are responsible for phagocytosis, or the ingestion of certain organisms or cellular debris.
  • Neutrophils: are the most abundant group, and like monocytes perform phagocytosis of organisms such as fungi and bacteria.
  • Basophils: are the least abundant group, and are involved in immunity response processes to support the release of substances such as histamines or serotonin.
  • Eosinophils: are responsible not only for phagocytosis but also for regulating allergic responses and hypersensitivity reactions that occur when a foreign organism enters the body.

Normal values

White blood cells are produced in the bone marrow and, as you have already seen, they play a vital role in the body. A normal white blood cell count is usually between 4,000 and 11,000 leucocytes per microlitre of blood.

If the count falls below 4,000, you should immediately seek specialist advice in order to determine the cause of the decline. The human body is prone to infections and bacteria if left without adequate levels of defense. Each type of leucocyte should be present in a certain number in order for the human body to function properly:

  • The number of neutrophils should not fall below 1,000
  • Lymphocytes should remain above 1,500
  • The normal range for monocytes is between 200-600
  • The normal range for basophils 0-300 per ml of blood.

A low eosinophil count may not produce any particularly worrying symptoms and so is not usually taken into consideration in the same way as the rest.

It should also be noted that an increase in white blood cells should also be monitored.

Possible causes of a decrease in white blood cells

There are numerous reasons for decrease in leucocytes . It may be due to straightforward, relatively common illnesses, such as the flu, or to much more serious complaints. These include:

  • Bacterial infections, influenza or diseases such as measles or malaria.
  • Aplastic anemia.
  • Lupus
  • Liver failure.
  • Leukemia: One of the most serious illnesses that causes a decrease in white blood cell count is leukemia. When the cancer affects the bone marrow, this greatly impacts the production of these blood cells.

Chemotherapy treatments and the use of certain drugs can also affect leucocyte count.

Consult a specialist

If you have a blood test when you're suffering from a cold or infection, it's likely that your white blood cell count will be low. But although it may seem unnecessary, it is always a good idea to consult a doctor after receiving a blood test that shows abnormal values. Only a specialist can determine the cause of this decline in leucocytes and the appropriate treatment.

A low white blood cell count is a symptom that should always be taken seriously; it indicates that your health is at risk because the body is not able to defend itself against bacteria, fungi and foreign organisms.


If you want to read similar articles to What Causes a Decrease in White Blood Cells?, we recommend you visit our Diseases & secondary effects category.

  • If you discover your white blood cells are below standard after an analysis, you should visit a hematologist
  • Don't be alarmed, the descent in white blood cells can be due to many factors, some don't have an impact on your health, that's why you should wait for your specialist's opinion.

Write a comment about What Causes a Decrease in White Blood Cells?

What did you think of this article?
hi sir, my son (age 8 month) sufferd from cough,cold,and fever for 4 weeks, there is no other symptoms .after using the medicine the symptoms were gone .after some hours again the symptoms .could be start .finally aal reports(test) says WBC count is high (15000) ,the doctors are using medicine to low of cells ,but no increment in his health
please advise sir to low (normal) WBC ?
OneHowTo Editor
As the article mentions, an increase of white blood cells is a symptom of a virus or infection, so make sure the doctors detect what it is so they can treat it appropriately.
Hope this helps
Oyelere Nike

Muhammad Farooq
My father (70 years old) is a cardiac patient. He has fever, and continuously declining WBCs (from 2.01 to 1.5 in last 7 days). He also feels problems in breathing, and has granuluma.
His doctor has asked for bone marrow biopsy. Plz advise how to proceed.
OneHowTo Editor
We advise you to wait for the results of the biopsy before starting a treatment. Your doctor should be able to advise you on that once he has his results.
hi sir. my brother sufferd from fever for 6weeks. symptoms are ceveare fever and cool shivering. there is no other symptoms. after using the medicine the symptoms were gone. aftter some hours again the symptoms Could be start. finally reports says red and whiteblood cells count is very low. but the doctors cannot recognise d wat is d decesase name. the doctors are using the medicine to growth of both cells. the count is grow while using d medicine. Again the count is fall. doctors are doing so many tests. but they cant recognise. please advise sir
OneHowTo Editor
Hi there,
You should always follow the doctors' recommendations, they are the people who know your brother's case better. If there has been a decrease in white blood cells, apart from medication there are certain foods that will help increase them, you'll find them in this article:
Here is another link with foods that increase red blood cells:

Hope this helps!
Dana Gough
What causes a lymphocytes count of 0.5 and percent of 10?
Hi sir, How to increase the white cells improve in the blood,then what is the reason for low white cells. Kindly reports soon for my medical emergencies
OneHowTo Editor
Hi there, in the article above you'll find the possible reasons for a low count of white blood cells. Visit your doctor and check for the specific reason for your low WBC count.
On the other hand, you can check out this article to know how to increase them:
Hope this helps

What Causes a Decrease in White Blood Cells?
What Causes a Decrease in White Blood Cells?

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