Causes and Symptoms of Low Monocyte Count

Did You Know?

In healthy individuals, monocyte count is just 1 to 3% of the total white blood cell (WBC) population present in the body.

Low monocyte count, also referred to as monocytopenia, can occur due to a wide range of medical conditions, some of which are discussed here.

Vitamin B12 Deficiency
Vitamin B12 is critical for the adequate production of white blood cells including monocytes. Our body depends on vitamin B12 to make enough monocytes. So, fewer than normal monocytes may also indicate vitamin B12 deficiency.

Bone Marrow Disorders
When the bone marrow is not functioning properly, the production of monocytes will surely go below the normal range. Following are the medical conditions that have been attributed to bone marrow failure, and that cause monocytopenia:

Aplastic Anemia
This is a blood disorder in which the bone marrow loses its ability to create adequate number of all types of cells, including red blood cells, white blood cells (monocytes), and platelets. As we know, the bone marrow produces stems cells, from which all other types of blood cells generate. In aplastic anemia, the stem cells fail to mature into healthy blood cells, which can lead to the shortage of monocytes.

Hairy Cell Leukemia
Hairy cell leukemia is a type of blood cancer that is marked by excessive production of B cells (a type of white blood cell) by the bone marrow. Microscopic examination of these cells reveal that they appear hairy, hence the name. However, too much presence of B cells often leads to a drop in monocyte count.

Lupus
Lupus is a chronic inflammatory condition in which the immune system ‘revolts’ against its own body tissues and invades different organs, including bone marrow. That is why bone marrow disorders are commonly diagnosed among lupus patients. The resulting bone marrow abnormality in these patients can cause the monocyte count to slip below the normal range.

Tuberculosis
This is a serious bacterial infection of the lungs, that often migrates to other parts of the body. When the bacteria infects the bone marrow, it can suppress its functioning, and cause low monocyte count.

Rheumatoid Arthritis
Rheumatoid arthritis (RA) is an autoimmune disorder that causes inflammation of the joints, and can also negatively affect the working of bone marrow. In fact, one study has pointed out to the presence of inflammatory lesions in people affected with rheumatoid arthritis. So, compared to healthy individuals, RA patients are likely to have a fewer number of monocytes.

HIV/AIDS
Bone marrow abnormalities are commonly reported in people who have contracted HIV. Moreover, this virus severely impairs the immune system. All this causes the production of monocytes that is far below the normal range.

Medications

Chemotherapy
Low monocyte count can also occur as a side effect of chemotherapy drugs or radiation therapy, which are commonly used for the treatment of cancer. Although this treatment helps in destroying cancer cells, it also lowers the production of healthy blood cells. This is because the treatment cannot differentiate between healthy cells and cancerous cells. As a result, after a therapy, the patient is likely to suffer from low monocyte count. Also, cancer treatment reduces the ability of bone marrow in making new blood cells, which also results in lower than normal production of monocytes.

Interferons
Oral interferons that are often prescribed for the treatment of viral hepatitis can also have a negative impact on the functioning of bone marrow. These medications tend to suppress the production of white blood cells including monocytes. Due to their suppressive effect, patients put on these medications show low monocyte count.

Corticosteroids
Anti-inflammatory medications like corticosteroids can also lower the production of monocytes. Corticosteroids, being immunosuppressive drugs, can cause a significant impact on monocyte functioning and cell count, in turn compromising one’s immunity.

The symptoms will differ depending upon what is causing the low production of monocytes. However, in general, the symptoms that can occur with low monocyte count are given here.

Fatigue
Low monocyte count means the person is likely to feel tired, more than usual. This abnormal tired feeling continues to haunt the individual throughout the day, enough to throw the day-to-day routine off track.

Weakness
With lower production of monocytes, general weakness sets in. Fewer infection-fighting cells means that the immune system faces difficulty in containing infection as well as maintaining overall health. This can make a person feel extremely weak.

Recurring Infections
Monocytes that are present in different tissues are known to protect the body from pathogens. Hence, when its count drops, the person frequently falls prey to infections. Also, it will take a longer time to recover from these infections.

Breathing Problems
Breathing trouble is yet another indication of this condition. Often, lower production of monocytes is accompanied by low RBC count. Red blood cells transport oxygen to every tissue of the body. Hence, low RBC count can reduce the amount of oxygen in the blood, which can lead to shortness of breath.