What Are Leukopenia, Neutropenia and Neutropenic Fever? Symptoms and Causes

What Is Leukopenia?

• Leukopeniais a below-normal white blood cell (leukocyte) count and increases infection risk. Leukocytes are reported in a complete blood count as WBC (white blood cells).
• Some blood cells are white blood cells; they are produced in the bone marrow, fight infections and are a vital component of the immune system.
• Leukopenia a complete blood count (hemogram) is detected through this test.
• The typical adult WBC reference range is 3,5–11,0 ×10³/µL. <3,5 ×10³/µL is considered leukopenia; severity increases as the value falls.

In this article, we will summarize the effects of leukopenia on the body, its causes, symptoms and available treatment options. We will also define a subtype of leukopenia, neutropenia.

There are five main white blood cell types; each protects against different infections:

• Neutrophils: Approximately %55–70 of total leukocytes; the first defense against bacteria and fungi.
• Lymphocytes: The second most common group; protection against viruses and specific immunity.
• Basophils: The rarest group; mediator release in allergic and inflammatory responses.
• Monocytes: The largest cells; a role in phagocytosis and tissue repair.
• Eosinophils: Defense against parasites and a role in allergic diseases.

Leukopenia subtypesare named according to the affected cell lineage: neutropenia, lymphopenia, monocytopenia, eosinopenia and basopenia.

What Is Neutropenia?

Neutropeniais a specific type of leukopenia; it means a reduction in neutrophils , the most common subgroup of white blood cells. In a complete blood count, it is usually reported as NEU (neutrophil).

Whereas leukopenia generally refers to a reduction in all white blood cells, neutropenia involves only neutrophils. Neutropenia is therefore much more important in determining infection risk.

Absolute Neutrophil Count (ANC – Absolute Neutrophil Count)is the most important indicator used to assess infection risk. Doctors calculate this value from blood tests and monitor it closely, particularly in patients receiving chemotherapy.

Neutropenia may be a sign of a bone marrow disease such as leukemia or may occur temporarily due to treatments such as chemotherapy. Therefore, regular complete blood count monitoring and early intervention are very important.

What Are the Symptoms of Leukopenia and Neutropenia?

Leukopenia or neutropenia generally causes no obvious symptoms. However, because the immune system is weakened, susceptibility to infections increases. Symptoms occurring in this situation are mostly related to infections that develop.

A low white blood cell count has no specific symptom of its own. Therefore, in patients receiving cancer treatment, even without symptoms, regular blood tests should be used for early detection of leukopenia .

Important: If a low white blood cell count is accompanied by fever , this condition is febrile neutropenia and requires urgent medical evaluation.

What Causes Leukopenia?

Leukopenia develops because white blood cell production decreases or existing cells are destroyed faster than normal. This often results from bone marrow dysfunction, infections or medication-related effects.

Conditions That May Cause Leukopenia

• Viral infections: Colds, influenza or other viral diseases may cause temporary bone marrow suppression.
• Blood cell and bone marrow diseases: Conditions such as aplastic anemia, myelodysplastic syndrome (MDS) or an overactive spleen (hypersplenism) may reduce production.
• Cancers: Leukemia and lymphomas in particular may directly affect bone marrow cells.
• Infectious diseases: HIV/AIDS, tuberculosis and some chronic bacterial infections may cause leukopenia.
• Autoimmune diseases: Leukocytes are destroyed in diseases such as lupus or rheumatoid arthritis, in which the immune system attacks its own cells.
• Congenital disorders: Genetic diseases such as Kostmann syndrome and myelokathexis affect bone marrow production.
• Malnutrition (inadequate nutrition): Deficiencies of vitamin B12, folate, copper or zinc may reduce white blood cell production.
• Sarcoidosis: This disease, in which small inflammatory foci develop in the body, may affect the bone marrow and impair cell production.

Treatments and Medicines That Can Cause Leukopenia and Neutropenia

Some treatments and medicines can also reduce white blood cell counts. Chemotherapy and radiotherapy used in cancer treatment are among the most common causes.

Drug-induced leukopenia generally occurs with the following groups:

• Interferons used to treat multiple sclerosis
• Epilepsy medicines: lamotrigine, sodium valproate
• Antidepressant and smoking-cessation medicines: bupropion
• Antipsychotics: clozapine
• Antibiotics: minocycline
• Immune suppressants (immunosuppressants): sirolimus, mycophenolate mofetil, tacrolimus, cyclosporine
• Steroids and some penicillin derivatives

These medicines may suppress production in the bone marrow or shorten the lifespan of white blood cells. Therefore, for patients taking long-term medication, regular complete blood count monitoring is important.

Grades of Leukopenia and Neutropenia

The white blood cell count is one of the most important indicators of the immune system’s resistance to infections. A temporary decrease in these cells is called pseudoleukopenia (false leukopenia) and is generally short-lived. However, if the low count persists, true leukopenia has developed.

Among leukocytes, particularly neutrophilsform the first line of defense against bacteria and fungi. Neutropenia is therefore a critical condition requiring close monitoring , particularly in patients receiving cancer treatment.

If a low white blood cell count is accompanied by fever , the condition is called febrile neutropenia . Febrile neutropenia, particularly in patients receiving chemotherapy, is a medical condition requiring emergency intervention , because even ordinary bacteria can cause serious infections when the body is defenseless.

How Are Leukopenia and Neutropenia Treated?

The main goal in treating leukopenia or neutropenia is to support renewed white blood cell production and reduce infection risk. Treatment varies according to the underlying cause.

• Drug-induced leukopenia: If a medicine causes a low white blood cell count, it may need to be stopped or replaced with an alternative under medical supervision. Patients should not stop taking medication on their own.
• Chemotherapy-related neutropenia: If white blood cell counts have fallen because of treatment, treatment may generally be paused briefly or the dose adjusted to allow the body to recover.
• G-CSF treatment: Known as a blood cell growth factor, G-CSF (Granulocyte Colony Stimulating Factor) injections — filgrastim, lenograstim, pegfilgrastim — accelerate neutrophil production in the bone marrow. They may be administered preventively, particularly after chemotherapy.

Care of the Neutropenic Patient

Because neutropenic patients have a weakened immune system, special measures should be taken to prevent infections.

• Nutrition: A healthy, balanced diet is recommended. The previously common approach of “avoiding raw vegetables and fruit” is no longer recommended because it does not significantly reduce infection risk. What matters is food safety and good hygiene.
• Hygiene: Handwashing, personal cleanliness and dental care should be maintained regularly.
• Avoiding injury: Preserving skin integrity prevents entry of infection.
• Rest: Adequate sleep and rest support the immune system.
• Regular follow-up: Blood counts should be checked at regular intervals.

Summary

Leukopenia and neutropenia are both part of the treatment process and safety parameters requiring monitoring in modern oncology. When detected early and managed appropriately, infectious complications can largely be prevented.