Monocytes are a type of WBCs or white blood cells that are created in the bone marrow. They are an integral component of the immune system and help fight infections.Their distinguishing feature is their big, notched kidney-shaped nucleus.

Medically termed as ‘monocytopenia,’ low monocyte count is harmful as it increases the risk to infections. Such risk is however dependent on the cause and severity of low monocyte count. In most cases, low monocytes often lead to or increase the vulnerability to infections by those types of bacteria that occur in the urinary tract, gastrointestinal tract, or the skin. Low monocytes can be diagnosed via a complete blood count test.Doctors may sometimes conduct a bone marrow biopsy to determine the cause of low monocyte count.

After creation, monocytes circulate across the bloodstream for 1 to 3 days before getting distributed to the lung, spleen, bone marrow, and liver tissues, where they mature as primary cells of the immune system. The spleen contains almost 50 percent of total monocytes in the body. The monocyte count in healthy people is only about 1 to 3 percent of the total WBC count in the body.

Symptoms of low monocytes

Low monocytes do not generally cause any symptoms. The manifested symptoms, if any, are generally dependent on the underlying condition that is causing the low monocyte count. For example, infections may cause coughing, fever, sore throat, frequent/urgent urination, chills, and flu-like symptoms.

Some of the common signs and symptoms of low monocytes are listed below:

• Low monocytes in the body results in weakness. Reduced number of monocytes burdens the immune system in its fight against infection as well as in maintaining the general health. This eventually leads to increased and extreme weakness.
• Patients with low monocyte count are also more prone to fatigue and tiredness. They are most likely to be exhausted and tired all through the day, thereby disrupting the daily routine.
• Low monocytes count is accompanied by low count of red blood cells. RBCs perform the function of carrying oxygen to the rest of the body. Reduced number of RBCs thus means that oxygen content in blood is low, which subsequently causes breathing problems like breathlessness.
• Monocytes protect the body from pathogens. Hence, low monocytes increases the risk to recurrent infections. Affected people may also take longer to get cured of such infections.

Causes of low monocytes

Low monocytes can be caused due to many reasons. Some of the medical conditions that commonly trigger a reduction in the monocyte countare listed below:

• Deficiency of vitamin B12: Vitamin B12 is vital to the process of sufficient number of WBCs and monocytes. A low monocyte count can thus be an indication of deficient levels of vitamin B12 in the body.
• Aplastic anemia: It is a blood disorder marked by reduced ability of the bone marrow to produce sufficient amounts of all types of cells, i.e., WBCs, RBCs, and platelets. It is known that the bone marrow created stem cells which then generates the different types of blood cells. The stem cells in people with aplastic anemia do not mature into healthy cells, thus causing low monocytes.
• AIDS/HIV: People with HIV/AIDS suffer from bone marrow anomalies. The disease also weakens the immune system severely. The combination of these factors causes a drastic drop in monocytes count.
• Hairy cell leukemia: It is a form of blood cancer characterized by increased production of WBC type B cells by the bone marrow. Such cells appear hairy when checked under a microscope. Excessive number of B cells can increase the risk to reduction in monocytes count.
• Tuberculosis: It is a severe form of bacterial infection that affects the lungs and typically travels to other organs of the body. When the bone marrow gets infected with the bacteria, then bone marrow function can get impaired leading to low monocytes.
• Lupus: It is an auto-immune disease and a chronic inflammatory condition wherein the immune system erroneously recognizes the organs and tissues of the body, like the bone marrow, as invaders and attacks it. This causes abnormalities of the bone marrow eventually resulting in a dip in the total number of monocytes. It may be noted that many lupus patients tend to suffer from bone marrow disorders.
• Rheumatoid arthritis: It is also an auto-immune condition that causes joints inflammation and adversely affects bone marrow functions. Abnormal working of the bone marrow then causes low monocytes.
• Medications: Therapies like radiation therapy and chemotherapy as well as medicines like corticosteroids and interferon also cause a low monocyte count.
  • Radiation therapy and chemotherapy are therapies that are used to treat cancer. They help destroy the cancer cells. However, since these treatment options cannot distinguish between cancerous and healthy cells, healthy blood cells also get destroyed during the therapy. The treatments also impair the bone marrow function and lower its capacity to produce new blood cells. These effects eventually result in low monocytes.
  • Corticosteroids are anti-inflammatory drugs that suppress the immune system. Such immune system suppression not only adversely affects monocyte functions and lowers its count, but also raises the risk of a weakened immune system.
  • Doctors prescribe oral interferon to treat viral hepatitis. But this drug can adversely affect bone marrow function and inhibit the production of WBCs and monocytes. Hence, patients taking interferon elicit low monocyte count.

Treatment of low monocytes

Treatment of low monocytes differs as per the overall health of the patient, the underlying cause, the severity of monocytopenia, and the presence of related symptoms and secondary infections.

• WBC production can be increased by administering WBC growth factor and infections can be treated with antibiotics, anti-fungal medicines, and other drugs. Other treatment options include corticosteroid therapy and intravenous immune globulin.
• Patients also need to consume a nutritious and balanced diet as well as follow guidelines during treatment to prevent the infection from spreading. Some common precautions include washing hands, wearing masks and/or gloves, and avoiding crowds to prevent contact with pathogens.