Potential Causes of Leukopenia

Introduction

A decrease in the number of white blood cells (WBCs) is referred to as leukopenia. There are several causes for leukopenia. It may be due to certain drugs, cancer, radiation and chemotherapy for cancer, stem cell transplant, surgery, steroids, or autoimmune disorders. 

The immune system of the body is directly affected when there is leukopenia. The body will have trouble in getting rid of infections, viruses, or bacteria if the number of white blood cells is not enough. To effectively treat the condition, the underlying cause of leukopenia must be first identified and treated.

Leukopenia

Leukopenia is the medical term for a low white blood cell count. Even though there is a debate over the number of white blood cells present in the blood, it is believed that in every microliter of blood, the number of white blood cells should not be less than 3,500. Between sexes, it may vary. The number of white blood cells also vary in different age groups. If the WBC count is low, it generally indicates a symptom of a medical illness. To return the number of WBCs back to normal, the underlying medical illness needs to be addressed first.

When WBCs are low, disease-fighting cells circulating in the blood also decreases. Usually, leukopenia is discovered when the doctor orders a diagnostic test for a certain condition. Sometimes, it is just discovered by chance. Results with other tests along with a low WBC count may indicate a specific illness. For this reason, doctors may request additional tests to help assess and diagnose your condition.

Symptoms of Leukopenia

Leukopenia itself is a symptom, which may indicate other underlying medical conditions. However, the common symptoms of leukopenia may include:

• Fever and chills
• Headaches
• Body aches

Other symptoms include:

• Hot flashes
• Fatigue
• Mood changes
• High fever
• Tongue ulcers
• Thrombocytopenia
• Liver disorders

Normal White Blood Cell (WBC) count

The normal range of WBCs for normal adults is 4,500-11,000/cubic millimeter of blood. In children, the range is slightly higher.

Causes of Leukopenia

1. Congenital Disorders

The way the body handles neutrophils can be interfered by certain congenital disorders such as Kostmann’s syndrome and myelokathexis. 

• Kostmann's syndrome - It is an inherited bone marrow disorder, wherein children are born without enough neutrophils. In the past, most children with this condition suffered from frequent bacterial infections that led to death. 

• Myelokathexis - It is an inherited WBC disorder that causes severe leukopenia and neutropenia.

2. Viral Infections

Viral infections tend to temporarily disrupt the function of the bone marrow, which produces white blood cells. Viruses can slow down the functioning of the bone marrow, which leads to leukopenia. 

3. Bone Marrow Diseases, Damage, or Suppression

When the bone marrow is damaged or suppressed, it can either cause an insufficient production of blood cells such as WBCs or cause an excess production of one type of WBC. Bone marrow diseases include:

• Leukemia
• Myelofibrosis
• Folate deficiency or vitamin B12 deficiency
• Myeloproliferative disorders
• Myelodysplastic syndrome
• Aplastic anemia

Exposure to certain toxins, chemicals, radiation, chemotherapy, and certain drugs may damage or suppress the bone marrow. When there is damage to the bone marrow, blood cells are less produced, which then leads to anemia and leukopenia. For the bone marrow to properly function, certain essential nutrients are required. 

4. Cancer

Leukopenia can be experienced when cancer spreads to the bone marrow. A low WBC count is also seen in other types of cancer such as lymphoma and leukemia. The quantity of dysfunctional white blood cells increases in leukemia. Thus, the ability of the bone marrow to produce normal blood cells is limited.

• Complications of Cancer Treatment - People who are having cancer treatments tend to have lower white blood cell counts. The WBC count significantly decreases when people with cancer are given chemotherapy drugs. In bone marrow cancer, can be a very low production of neutrophils, which leads to leukopenia.

The bone marrow is suppressed during chemotherapy and radiation, which is why people undergoing cancer treatments are more susceptible to infections. To prevent serious complications due to low WBC counts, treatments are sometimes modified.

5. Hypersplenism

Hypersplenism is a disorder that causes the spleen to prematurely destroy blood cells, which leads to anemia and leukopenia. The function of the spleen is to get rid of old blood cells in the body, but in the case of an overactive spleen, the process of cell removal accelerates even when the cells are still properly functioning.

6. Overwhelming Infections

The body’s WBCs may get depleted due to severe infections. Some severe infections can cause life-threatening complications called sepsis.

7. Drugs

Specific medications can damage the bone marrow or white blood cells. There are certain medications that can cause leukopenia. They include:

• Antipsychotic medications such as clozapine
• Antiepileptic agents, which include lamotrigine and sodium valproate
• Interferons (IFNs) for the treatment of multiple sclerosis
• Immunosuppressive drugs for transplant patients such as sirolimus, tacrolimus, cyclosporine, and mycophenolate mofetil
• Antibiotics such as minocycline and penicillin may also cause leukopenia

8. Autoimmune Disorders/Diseases of the Immune System

An autoimmune disorder is a condition wherein the immune system mistakenly damages healthy cells and tissues in the body. In autoimmune disorders, the immune system destroys healthy white blood cells, which lead to leukopenia. An example of an autoimmune disease is lupus.

The body’s white blood cell count may also reduce due to HIV/AIDS. In an HIV infection, the white blood cells are attacked, which makes the immune system weaker. Thus, the body’s ability to fight even the simplest infection is lost. 

9. Anorexia Nervosa

Another cause of leukopenia is anorexia nervosa. In this type of eating disorder, there is an abnormally low body weight due to intentional starvation. According to the University of Virginia Health System, many anorexic patients have low white blood cell counts. Leukopenia occurs due to frequent vomiting and a limited diet. Hence, the bone marrow does not get sufficient nutrients that are required for the body to produce enough white blood cells.

10. Sarcoidosis 

Sarcoidosis is a systemic disease characterized by the formation of granulomas in multiple areas of the body. When these granulomas form in the bone marrow, it can significantly cause a low white blood cell count. 

Other Medical Conditions

The following conditions may also cause leukopenia:

• Thyroid disorders
• Rheumatoid arthritis
• Parasitic infections
• Typhoid fever
• Influenza
• Dengue and malaria
• Tuberculosis
• Rickettsial infections
• Deficiency of minerals such as copper and zinc