Published May 10, 2023 by

Low White Blood Cell Count: Definition, Causes, Symptoms, Diagnosis & Treatment


A low white blood cell count indicates a drop in disease-preventive blood cells.

The definition of a low white blood cell count varies from one laboratory to another.  This is because each laboratory establishes its own reference range based on the people it serves.  A count of less than 3,500 white blood cells per microliter of blood is typically regarded as low in adults.  For children, the expected count depends on age.

Some people may have lower than expected white blood cell counts and still be healthy.  For example, black-skinned people tend to have lower counts than white-skinned people.


White blood cells are made in the bone marrow, the spongy tissue located inside some of the longest bones.  Conditions that affect the bone marrow are the most common causes of a low white blood cell count.  Some of these conditions are present from birth (congenital).

Causes of a low white blood cell count include the following:

*Aplastic anemia



 -Epstein–Barr virus

*Hepatitis A

*Hepatitis B





*Rheumatoid arthritis


*Malnutrition as well as a vitamin shortage.

*Medications, such as antibiotics


*Sepsis  (a severe bloodstream infection)



A low white blood cell or leukocyte count does not lead to specific symptoms.  You have symptoms because you get infections often.  Sometimes the infections are unusual, they are infections that most people do not get.
Symptoms of infections can start abruptly or slowly and include:

* Rash
*Swollen lymph nodes
* Painful sores in the mouth and anus (the opening at the end of the digestive tract where stool comes     out)
*Fever, chills, or sweats. 
*Diarrhea that does not go away or comes with blood.
*Severe nausea and vomiting
*Inability to eat or drink.
*Extreme weakness.

Diagnosis :

Doctor will likely recommend tests to diagnose a low lymphocyte count.  Some of these analyzes may need to be repeated.

A complete blood count with differential looks at the number of lymphocytes, as well as red blood cells, platelets, and other types of white blood cells in the blood.

Flow cytometry measures the levels of different types of lymphocytes: T cells, B cells, and natural killer cells.  This helps doctors find the underlying cause of the lymphopenia.

Immunoglobulin levels assays measure levels of antibodies called immunoglobulins, made by B lymphocytes. Total levels may be low due to low B lymphocyte counts, or it is likely that some groups of B lymphocytes, even if present, are dysfunctional and do not produce normal amounts of some subgroups of antibodies.

Doctors treat a low white blood cell or leukocyte count using:

*Antibiotics to treat any infection

*Medicines to force your body to make more white blood cells

*Treatment for any conditions that may be causing the low count.