What happens when your white blood cells are too low

White blood cells, also known as leukocytes, help protect the body against infections, bacteria, viruses and diseases. These essential part of the immune system are produced in the bone marrow and are present in the blood and lymph tissue. White blood cells (WBC) come in different types, and the blood normally contains a certain percentage for each type. This is what doctors check when they request tests that measure a person’s WBC count.

Why Do Doctors Check Your WBC Count?

The WBC count is usually included in a test that measures your complete blood count (CBC). A low white blood cell count or a high blood cell count may indicate an infection or an undiagnosed condition such as a blood disorder, an autoimmune diseases or an immune deficiency. The WBC count can help doctors detect and provide treatment for these potential conditions as well as help monitor the effectiveness of radiation treatment or chemotherapy for cancer patients.

What Is the Normal WBC Count?

People’s WBC count may vary depending on their age. Infants usually have a higher WBC count which gradually decreases as they get older. The table below shows the normal WBC ranges per microliter of blood (mcL).

Symptoms of an Abnormal WBC Count

An abnormal WBC count may either be lower or higher than the normal range. The common symptoms of a low WBC, also known as leukopenia, include body aches, chills, fever and headaches. If you have these symptoms, please schedule an appointment with your doctor and he/she may recommend a WBC count.

On the other hand, a high WBC count, also known as leukocytosis, usually doesn’t cause symptoms, although the underlying condition that’s causing it may show its own signs.

Risk Factors of an Abnormal WBC Count

A low WBC count may be triggered by the following factors or conditions:

• Autoimmune disorders
• Bone marrow damage or disorder
• Certain medications (i.e., antibiotics)
• Human immunodeficiency virus (HIV)
• Liver and spleen diseases
• Lupus
• Lymphoma
• Radiation therapy
• Severe infections

Meanwhile, a high WBC count may be triggered by the following factors or conditions:

• Asthma
• Certain allergies
• Certain infections (i.e., tuberculosis)
• Certain medications (i.e., corticosteroids)
• Exercise
• Inflammatory conditions (i.e., arthritis and bowel disease)
• Leukemia
• Pregnancy
• Smoking
• Stress
• Tissue damage
• Tumors in the bone marrow

How to Prepare for a WBC Count

First, you have to schedule an appointment with your doctor to get a test request and then schedule an appointment with the laboratory for blood extraction. Certain medications may either lower or increase your WBC count, so please let your physician know if you’re under medication. Some of the drugs that may interfere with your WBC count results are as follows:

• Antibiotics
• Anticonvulsants
• Antihistamines
• Chemotherapy medication
• Clozapine
• Corticosteroids
• Diuretics
• Heparin
• Quinidine
• Sulfonamides

Final Thoughts

If your laboratory test results show that you either have a low or high WBC count, your doctor may recommend a treatment plan and may also recheck your WBCs from time to time. But if your WBCs are within the normal range, great. Just keep doing things that can help boost your immune system and keep you healthy, such as eating fruits and vegetables, getting enough sleep, limiting your sugar intake, exercising regularly, managing your stress levels and staying hydrated. Have a great day ahead!

Sources:
National Cancer Institute
Healthline

White blood cells (WBCs) fight infections from bacteria, viruses, fungi, and other pathogens (organisms that cause infection). One important type of WBC is the neutrophil. These cells are made in the bone marrow and travel in the blood throughout the body. They sense infections, gather at sites of infection, and destroy the pathogens.

When the body has too few neutrophils, the condition is called neutropenia. This makes it harder for the body to fight off pathogens. As a result, the person is more likely to get sick from infections. In general, an adult who has fewer than 1,000 neutrophils in a microliter of blood has neutropenia.

If the neutrophil count is very low, fewer than 500 neutrophils in a microliter of blood, it is called severe neutropenia. When the neutrophil count gets this low, even the bacteria normally living in a person's mouth, skin, and gut can cause serious infections.

A person with cancer can develop a low WBC count from the cancer or from treatment for the cancer. Cancer may be in the bone marrow, causing fewer neutrophils to be made. The WBC count can also go down when cancer is treated with chemotherapy drugs, which slow bone marrow production of healthy WBCs.

When your blood is tested, ask for your WBC count and specifically, your neutrophil count. If your counts are low, do what you can to prevent infections. Know the signs of infection and what to do if you have them.

Prevent infections by taking the following measures:

• Be careful with pets and other animals to avoid catching infections from them.
• Practice safe eating and drinking habits.
• Wash your hands often with soap and water.
• Stay away from people who have symptoms of an infection.
• Avoid traveling and crowded public places.

If you have any of the following symptoms, call your health care provider:

• Fevers, chills, or sweats. These may be signs of infection.
• Diarrhea that does not go away or is bloody.
• Severe nausea and vomiting.
• Being unable to eat or drink.
• Extreme weakness.
• Redness, swelling, or drainage from any place where you have an IV line inserted into your body.
• A new skin rash or blisters.
• Pain in your stomach area.
• A very bad headache or one that does not go away.
• A cough that is getting worse.
• Trouble breathing when you are at rest or when you are doing simple tasks.
• Burning when you urinate.

Neutropenia and cancer; Absolute neutrophil count and cancer; ANC and cancer

American Cancer Society website. Infections in people with cancer: why people with cancer are more likely to get infections. www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/infections/infections-in-people-with-cancer.html. Updated March 13, 2020. Accessed July 30 2, 2021.

Centers for Disease Control and Prevention website. Preventing infections in cancer patients. www.cdc.gov/cancer/preventinfections/index.htm. Updated November 10, 2020. Accessed July 30, 2021.

Freifeld AG, Kaul DR. Infection in the patient with cancer. In: Niederhuber JE, Armitage JO, Kastan MB, Doroshow JH, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, PA: Elsevier; 2020:chap 34.

Updated by: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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