White blood cells, also known as leukocytes, are an important part of your body’s immune system. They defend against infections and diseases by identifying and destroying foreign invaders like bacteria, viruses, and fungi. A low white blood cell count, medically termed leukopenia, indicates your body has fewer of these protective cells than it needs. When this count drops, your ability to fight illness diminishes, increasing infection risk.
Types and Roles of White Blood Cells
Your immune system relies on several distinct types of white blood cells, each performing specialized functions. Neutrophils are the most abundant type, typically making up 55% to 70% of the total white blood cell count, and they primarily target bacterial and fungal infections. Lymphocytes are important for recognizing and attacking viruses, producing antibodies, and identifying abnormal cells.
Monocytes clean up cellular debris and communicate with other immune cells to identify threats. Eosinophils fight parasitic infections and play a role in allergic responses, while basophils also contribute to allergic reactions by releasing substances like histamine. A reduction in any of these types can weaken the body’s defense mechanisms.
Medical Conditions Leading to Low Counts
Several medical conditions can significantly reduce white blood cell counts, often by affecting their production or lifespan. Problems originating in the bone marrow, the spongy tissue inside bones where blood cells are made, are frequent causes. Conditions such as aplastic anemia lead to the bone marrow failing to produce enough white blood cells, red blood cells, and platelets. Certain cancers like leukemia, lymphoma, or myelodysplastic syndromes can also damage the bone marrow, causing an insufficient production of healthy white blood cells.
Infections, particularly severe or chronic ones, can deplete white blood cells. Viral infections such as HIV, hepatitis, influenza, and even the common cold can temporarily suppress bone marrow function or directly destroy white blood cells. Overwhelming bacterial infections like sepsis can cause the body to use up white blood cells faster than they can be produced.
Autoimmune diseases occur when the immune system mistakenly attacks healthy body tissues. Conditions like lupus and rheumatoid arthritis can target and destroy the body’s own white blood cells. Additionally, an enlarged or overactive spleen, a condition known as hypersplenism, can trap and destroy white blood cells at an accelerated rate.
Medications and Other Factors Affecting White Blood Cells
Beyond medical conditions, specific medications and other factors can lead to leukopenia. Chemotherapy drugs, a common cause, are designed to kill rapidly dividing cancer cells but also affect healthy fast-growing cells, including white blood cells in the bone marrow. Immunosuppressants, used to prevent organ transplant rejection or manage autoimmune diseases, intentionally suppress white blood cell production.
Certain other medications may also lead to lower counts. These include some antibiotics, antipsychotics, anticonvulsants, and antithyroid drugs. Exposure to certain environmental toxins, although less common, can also harm bone marrow function. Benzene and some pesticides have been linked to reduced white blood cell production.
Nutritional deficiencies can impair the body’s ability to produce white blood cells effectively. Severe deficiencies in specific vitamins like B12 and folate, or minerals such as copper, can disrupt the cell production process in the bone marrow. Chronic heavy alcohol consumption has also been associated with reduced white blood cell counts.
When to Consult a Healthcare Professional
Recognizing when to seek medical advice for a low white blood cell count is important, as it often does not cause direct symptoms. Instead, symptoms usually arise from increased susceptibility to infections. These can include frequent or unusual infections, such as those that are more severe or take longer to heal than expected.
Other signs that warrant medical attention include unexplained fever, chills, persistent fatigue, or mouth sores that do not heal. If you are receiving medications known to affect white blood cell counts, such as chemotherapy, or have an underlying health condition, discuss any new or worsening symptoms with a doctor.
Investigating and Managing Low Counts
Healthcare professionals typically begin investigating a low white blood cell count with a complete blood count (CBC). This standard blood test measures the total number of white blood cells and provides a differential count, detailing the levels of each specific type. If the CBC indicates leukopenia, further tests are usually conducted to pinpoint the underlying cause.
These investigations might include a bone marrow biopsy to assess bone marrow health, or specialized blood tests to detect infections or autoimmune markers. Management of leukopenia focuses on addressing the root cause. Treatment strategies can involve adjusting medications, treating underlying infections with antibiotics or antiviral drugs, or managing autoimmune conditions. Growth factors may also be administered to stimulate the bone marrow to produce more white blood cells.