What Does a Low Neutrophil Count Indicate?

When there's a low neutrophil count, measures should be taken to prevent possible bacterial or fungal infections. Learn more here.
What Does a Low Neutrophil Count Indicate?

Last update: 17 December, 2022

A low neutrophil count indicates the development of neutropenia, a form of leukopenia that reduces the body’s ability to fight bacterial and fungal infections. This implies that the inflammatory response against such antigens is ineffective, and serious complications can result.

However, there are several reasons why a low neutrophil count can occur. These range from infections and drug reactions, to vitamin deficiency and some diseases. In today’s article, we’re going to tell you more about the causes and treatments.

What are neutrophils and what is their importance?

In the body, white blood cells or leukocytes are responsible for fighting various infections, whether they’re caused by viruses, bacteria, fungi, or other organisms.

Neutrophils are precisely the most abundant type of white blood cell in the blood since they account for 70% of the total number of leukocytes. Hence the importance of maintaining a high count of neutrophils, since their quantitative alterations cause some problems.

Their main function is to help the immune system fight diseases of infectious origin, taking the invading agent -particularly bacteria and fungi- and then directing and expelling it.

When the body is attacked, neutrophils are the first immune cells to detect the point of infection. Because of their gel-like consistency, they have the facility to pass through the walls of blood vessels to migrate to the affected tissues and destroy pathogens.

Values indicating low blood neutrophil counts

Normal neutrophil levels in a healthy adult range from 2000 to 7500 per microliter of blood. Lower counts are classified according to their severity:

  • Mild neutropenia: This occurs when the absolute neutrophil count ranges from 1000 to 1500/µL and the risk of infectious disease is relatively minor.
  • Moderate neutropenia: This is when the neutrophil count ranges from 500 to 1000/µL and the risk of infection is moderate.
  • Severe neutropenia: This is a very low neutrophil count, less than 500 µL; the risk of infection is high.
low neutrophil blood count
Low neutrophils are indicative of neutropenia. It can be mild, moderate, or severe.

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Why does a low neutrophil count occur?

As stated in an article published by the Mayo Clinic, there are several factors that are associated with a low neutrophil count. In particular, two main causes are considered:

  1. A decreased production of these leukocytes
  2. Leukocytes are destroyed within a short time after being produced

Both cases are related to some medical conditions and habits that affect immune health, such as the following:

  • Viral, bacterial, or parasitic infections: For example AIDS, tuberculosis, malaria, or the Epstein-Barr virus (EBV).
  • Drugs that affect bone marrow and neutrophils: The most at risk are dipyrones, ticlopidine, calcium dobesilate, and antithyroid drugs. To a lesser extent are antiepileptics, such as phenytoin or carbamazepine.
  • Oncological treatments such as chemotherapy, radiotherapy, and certain cancer treatment drugs. These, in general, damage neutrophils during the process.
  • Vitamin B12 or folate deficiency: This is related to megaloblastic anemia.
  • Cancer or other bone marrow diseases such as leukemia, myelodysplastic syndrome, aplastic anemia, and myelofibrosis.
  • Congenital disorders of bone marrow function. For example, this includes Kostmann’s syndrome.
  • Autoimmune destruction of neutrophils (as a primary condition or related to Felty’s syndrome).
  • Other autoimmune diseases such as granulomatosis with polyangiitis (or Wegener’s granulomatosis) and lupus.
  • Hypersplenism: This is the premature destruction of blood cells by the spleen.

There are other factors that are related to a low white blood cell count, which can be closely linked to various diseases; in addition to those previously mentioned, we have:

  • Hepatitis A and B
  • Hyperthyroidism
  • Rheumatoid arthritis
  • Congenital diseases
  • Infiltrative processes of the bone marrow
  • Excessive consumption of alcoholic beverages
  • Prolonged use of certain antibiotics and diuretics

The symptoms of low neutrophils

A low neutrophil count is usually diagnosed when severe infections or sepsis develop. Many mild cases go unnoticed because the symptoms are not entirely obvious.

The presenting manifestations may vary depending on the severity of the neutropenia and also depending on the type of underlying infection or disease.

In other words, rather than signs of neutropenia, it’s the symptoms of infections that are manifested. As such, patients may experience:

  • A sore throat
  • Frequent diarrhea
  • A moderate or a high fever
  • Recurrent headaches
  • Susceptibility to infections
  • Lesions or ulcers in the mouth and the anal region
  • Inflammation of the lymph nodes
  • Skin infections and wounds that take time to heal
  • Burning sensation when urinating and changes in urination

Diagnosis and treatment

Diagnosis of neutropenia is made with a neutrophil count through a complete blood count. If the results are uncertain, the physician may suggest an adjunctive test such as a biopsy.

In adults, the diagnosis is positive when the absolute neutrophil count is less than 1500 per microliter of blood. The cell count to indicate neutropenia in children varies with age.

low neutrophil count
A complete blood count can determine the level of neutrophils.

Treatment for a low neutrophil count is based on controlling the underlying cause and monitoring the patient’s general health to prevent infection.

Of course, treatment management varies from case to case, depending on the severity of the disease. The most common usually include the following:

  • Granulocyte transfusions
  • Antibiotic and antifungal medications for infections
  • Intravenous corticosteroid or immunoglobulin treatment 
  • Administration of white blood cell growth factors, if neutropenia is very severe

Possible complications

As mentioned, neutropenia is considered severe when the neutrophil count is very low: below 500 per microliter of blood. When this happens, dangerous infections can occur, compromising the patient’s health.

And these are not only caused by external microorganisms, but even by bacteria that normally live in the body, both on the skin and in the mucous membranes of the mouth or intestine.

When to go to the doctor

When neutropenia has been diagnosed, it’s necessary to be attentive to various signs. In this order of ideas, it’s recommended to call the doctor if symptoms such as the following are present:

  • Fever greater than 38° C, with chills or cold sweat
  • Shortness of breath
  • A cough that comes on suddenly
  • A sore throat or neck pain
  • Difficulty urinating
  • Vomiting and diarrhea
  • Vaginal discharge
  • Redness and swelling around wounds

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Preventative measures to avoid infections

Those patients whose low neutrophil count has its origin in infection should also implement some preventive measures. For example, regular hand washing and the use of gloves and face masks can limit the risk of infections.

Similarly, good hygiene habits should be followed when handling food for cooking and consumption. In addition, it’s recommended not to come into close contact with people showing symptoms of infection and to avoid crowded places.

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The contents of this publication are for informational purposes only. At no time can they serve to facilitate or replace the diagnoses, treatments, or recommendations of a professional. Consult with your trusted specialist if you have any doubts and seek their approval before beginning any procedure.