What are monocytes and when are they considered elevated?
Monocytes are formed in the bone marrow, circulate in the blood for several hours, and then go into the tissues where they become macrophages. The analysis indicates both the percentage and the absolute number. The second is more important: if the total number of leukocytes is reduced, the percentage of monocytes can increase with their normal absolute content - this is relative monocytosis, which usually does not mean anything. An increase in the absolute number of monocytes above laboratory reference values is considered true. A one-time result is always assessed together with well-being and other indicators.
- Monocytes are part of the innate immune system
- In tissues they transform into macrophages
- Estimate the absolute number, not just the percentage
- Relative monocytosis is usually not significant
- A single deviation requires repeat analysis
Infections and recovery from illness
The most common cause is an infectious process. Monocytes increase in prolonged bacterial infections, tuberculosis, infective endocarditis, brucellosis, as well as in viral diseases, such as infectious mononucleosis. Monocytosis is very typical during the recovery period: when the body finishes the fight and removes the effects of inflammation, the number of monocytes temporarily increases. Therefore, a test taken one to two weeks after the infection often shows a moderate increase, which goes away on its own.
- Persistent bacterial infections
- Tuberculosis
- Infectious mononucleosis
- Infective endocarditis
- The recovery period after illness
- Parasitic infections
Chronic inflammation and other causes
Monocytosis accompanies chronic inflammatory and autoimmune diseases: rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, sarcoidosis. It occurs in liver diseases, after removal of the spleen, with prolonged stress and taking certain drugs that stimulate hematopoiesis. A moderate increase occurs in smokers and after surgery. In all these cases, monocytes are not an independent problem, but a reflection of the underlying process, and they decrease as it is treated.
- Rheumatoid arthritis and lupus
- Inflammatory bowel diseases
- Sarcoidosis
- Chronic liver diseases
- Condition after removal of the spleen
- Smoking and taking blood stimulants
When to exclude blood diseases
A persistent increase in the absolute number of monocytes that persists for more than three months without an obvious cause requires the attention of a hematologist. This happens with chronic myelomonocytic leukemia, myelodysplastic syndromes, some lymphomas and after chemotherapy. The accompanying changes are alarming: a decrease in hemoglobin and platelets, the appearance of immature cells in the formula, an enlargement of the spleen and lymph nodes, fever, night sweats and weight loss. Elevated monocytes themselves without these signs rarely mean a blood disease.
- Monocytosis longer than three months
- Decreased hemoglobin and platelets
- Immature cells in the leukocyte formula
- Enlarged spleen and lymph nodes
- Fever, sweating, weight loss
What to do with elevated monocytes
If you feel good and the increase is small and was after a recent infection, it is usually enough to repeat a general blood test after three to four weeks. Before taking the exam, it is important to follow the rules: on an empty stomach, in the morning, without physical activity and smoking the day before. If monocytosis persists, the doctor evaluates the entire formula, prescribes CRP, according to indications, a chest x-ray, ultrasound of the lymph nodes and abdominal organs, and examination for infections. If there is a persistent increase and alarming signs, they are referred to a hematologist. Self-medication and taking immunostimulants are not necessary.
- Repeat blood test in 3–4 weeks
- Donate blood in the morning on an empty stomach
- Evaluate the entire formula, not just one indicator
- Take CRP and, if necessary, take a chest x-ray
- Ultrasound of lymph nodes when they are enlarged
- Consultation with a hematologist for persistent monocytosis