Monocytosis or a monocyte count higher than 800/µL in adults indicates that the body is fighting an infection. Some conditions that may attribute to a high monocyte count include:
- Viral infections such as infectious mononucleosis, mumps, and measles
- Parasitic infections such as malaria or kala-azar
- Chronic inflammatory disease such as sarcoidosis
- Chronic myelomonocytic leukemia (a cancerous condition where the monocytes in the bone marrow begin to grow out of control)
- Sarcoidosis (growth of tiny collections of inflammatory cells in different parts of the body)
- Langerhans cell histiocytosis (a disorder where the cells called histiocytes and eosinophils flourish in the lungs, often causing scarring)
Some researchers believe that high monocyte levels are linked to cardiovascular diseases. Early detection of increased monocytes could help evaluate heart health management. Moreover, a high to low monocyte count ratio can help identify prognosis in people with ulcerative colitis.
What are monocytes?
In general, monocytes are the largest white cells in the blood. Monocytes are capable of motion and eating of infectious agents, red cells, and other large particles. The functions of monocyte include:
- Help other white blood cells eliminate dead and damaged tissues
- Destroy cancer cells
- Regulate immunity against foreign substances
The average monocytes range from 2-8% of the circulating white blood cells. Monocytes are produced in the bone marrow and then enter the blood. After being in the blood for a few hours, monocytes move to different tissue. Here, they are converted into macrophages, which act as scavenger cells of the immune system.
A high or low monocyte count itself does not cause any symptoms. However, you may experience symptoms of the conditions that may alter the monocyte count.
Monocytes are a type of white blood cells. A white blood count measures the number of white cells in your blood. White cells are involved in fighting off infections and other diseases. There are five major types of white blood cells:
- Basophils discharge chemicals to help fight allergies and infectious agents.
- Eosinophils fight parasites and cancer cells and assist with an allergic response.
- Monocytes act as the presenting cells for parasites and fungal proteins.
- Lymphocytes create antibodies against bacteria, viruses, and other invaders.
- Neutrophils kill bacteria and fungi.
Reference ranges for different white blood cell counts are described below:
- Neutrophils: 2,500-8,000 per mm3 (55-70%)
- Lymphocytes: 1,000-4,000 per mm3 (20-40%)
- Monocytes: 100-700 per mm3 (2-8%)
- Eosinophils: 50-500 per mm3 (1-4%)
- Basophils: 25-100 per mm3 (0.5-1%)
What does a low monocyte count mean?
A low monocyte count or monocytopenia is a reduction in the monocyte count to less than 500/µL. Monocytopenia may indicate the following conditions:
- Chemotherapy-induced myelosuppression
- Infections such as human immunodeficiency virus (HIV) infection, Epstein-Barr virus infection, or adenovirus infection
- Corticosteroid or immunoglobulin therapy
- Neoplastic disorders (they are conditions that cause tumor growth)
- Gastric or intestinal resection (surgery to remove a part or whole of the stomach or intestine)
- Hematopoietic cell mutation involving GATA2 (a genetic change that affects how their blood and immune systems develop)
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