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Table of Contents

Causes

Blood Tests

Related Tests

Treatment

Prevention

A high monocyte count (monocytosis) is a blood test finding that can indicate an infection, an autoimmune disease, or a blood disorder. High monocytes can also be a side effect of medication.

Monocytes are white blood cells, part of the immune system that helps fight infections and diseases. There are no symptoms of high monocytes. Monocytosis doesn’t cause health problems but is an indication of an illness or underlying condition, which could be minor or serious.

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Close-up Of Doctor Taking Blood Sample From Patient’s Arm in Hospital

Causes of High Monocytes

If your blood test identifies a high monocyte count, or monocytosis, it could mean a few different things. Monocytosis happens when your bone marrow is producing too many monocytes, a type ofwhite blood cell. These help your body identify and fight infection from viruses, bacteria, and other microbes.

Monocytosis can be temporary, like when the body needs more monocytes to fight a bacterial or viral infection. Long-term overproduction of monocytes, however, may indicate a chronic health condition.

High monocyte levels are associated with:

Physical, emotional, or mental stress can temporarily increase monocyte levels. Even exercise or a poor night’s sleep can raise monocytes. When you are under chronic stress, prolonged high monocyte levels can occur.Elevated monocytes are also found in mental health conditions, including depression. Research suggests specific monocytes may be useful biomarkers for identifying people with depression at risk of suicide.

Physical, emotional, or mental stress can temporarily increase monocyte levels. Even exercise or a poor night’s sleep can raise monocytes. When you are under chronic stress, prolonged high monocyte levels can occur.

Elevated monocytes are also found in mental health conditions, including depression. Research suggests specific monocytes may be useful biomarkers for identifying people with depression at risk of suicide.

Monocytes Blood Test

Since high monocytes do not cause any symptoms, the only way to know they are imbalanced is with a blood test.

Monocytes are assessed using acomplete blood count (CBC)with differential. This blood test measures blood cells and provides a detailed breakdown of the number and proportion of different types.

Normal Monocyte Range

High monocyte levels that last longer than three months are considered persistent and warrant further testing.

Your healthcare provider will assess your monocyte number in context with the other CBC results. Some issues that cause monocytosis will cause other numbers to be off, giving clues to the cause.

To help pinpoint a cause, your healthcare provider may order additional diagnostic tests, such as:

Treatment for monocytosis depends on the cause. For example, antibiotics are prescribed to treat a bacterial infection. People with leukemia (cancers of the blood) may be treated with chemotherapy or other cancer treatments.

Sometimes, a related condition may need to be treated as well. For example,anemiamay need to be treated with therapies such as a blood transfusion orerythropoietin(a hormone that stimulates red blood cell production).

Monitoring During TreatmentDuring treatment, you may need to have your monocyte levels checked repeatedly. Testing at regular intervals helps to monitor the effectiveness of treatment. For some types of leukemia, all blood cells are periodically monitored to determine the effects of treatment.

Monitoring During Treatment

During treatment, you may need to have your monocyte levels checked repeatedly. Testing at regular intervals helps to monitor the effectiveness of treatment. For some types of leukemia, all blood cells are periodically monitored to determine the effects of treatment.

Summary

Monocytes are a type of white blood cell that play a role in your immune system. Monocytosis (a high monocyte count) can occur along with changes in other leukocytes (white blood cells), or it may be the only indication of a medical problem.

Common causes of a high monocyte count include infections, leukemia, and autoimmune diseases like rheumatoid arthritis, lupus, and ulcerative colitis.

If you have a high monocyte count, you may need diagnostic testing to determine the cause. You also may need treatment for any underlying medical illness that is causing monocytosis.

7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: A systematic approach to a common hematologic finding.Curr Hematol Malig Rep. 2021;16(3):267-275. doi:10.1007/s11899-021-00618-4Hirose S, Lin Q, Ohtsuji M, Nishimura H, Verbeek JS.Monocyte subsets involved in the development of systemic lupus erythematosus and rheumatoid arthritis.Int Immunol. 2019 Oct 16;31(11):687-696. doi:10.1093/intimm/dxz036.Kim KY, Shin KY, Chang KA.Potential inflammatory biomarkers for major depressive disorder related to suicidal behaviors: a systematic review.Int J Mol Sci. 2023;24(18):13907. doi:10.3390/ijms241813907Hayley S, Hakim AM, Albert PR.Depression, dementia and immune dysregulation.Brain. 2021;144(3):746–60. doi:10.1093/brain/awaa405Arslanoğlu E, Işık ME, Kara KA, Yigit F, Çine N, Tunçer E, Ceyran H.Preoperative monocytosis is predictable at diagnosis for RT-PCR negative COVİD-19 paediatric cardiac surgery patients.Cardiol Young.2021:1-5. doi:10.1017/S104795112100319XMałujło-Balcerska E, Pietras T.Deiodinase types 1 and 3 and proinflammatory cytokine values may discriminate depressive disorder patients from healthy controls.J Clin Med. 2023;12(19):6163. doi:10.3390/jcm12196163Cleveland Clinic.Monocytes.

7 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: A systematic approach to a common hematologic finding.Curr Hematol Malig Rep. 2021;16(3):267-275. doi:10.1007/s11899-021-00618-4Hirose S, Lin Q, Ohtsuji M, Nishimura H, Verbeek JS.Monocyte subsets involved in the development of systemic lupus erythematosus and rheumatoid arthritis.Int Immunol. 2019 Oct 16;31(11):687-696. doi:10.1093/intimm/dxz036.Kim KY, Shin KY, Chang KA.Potential inflammatory biomarkers for major depressive disorder related to suicidal behaviors: a systematic review.Int J Mol Sci. 2023;24(18):13907. doi:10.3390/ijms241813907Hayley S, Hakim AM, Albert PR.Depression, dementia and immune dysregulation.Brain. 2021;144(3):746–60. doi:10.1093/brain/awaa405Arslanoğlu E, Işık ME, Kara KA, Yigit F, Çine N, Tunçer E, Ceyran H.Preoperative monocytosis is predictable at diagnosis for RT-PCR negative COVİD-19 paediatric cardiac surgery patients.Cardiol Young.2021:1-5. doi:10.1017/S104795112100319XMałujło-Balcerska E, Pietras T.Deiodinase types 1 and 3 and proinflammatory cytokine values may discriminate depressive disorder patients from healthy controls.J Clin Med. 2023;12(19):6163. doi:10.3390/jcm12196163Cleveland Clinic.Monocytes.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: A systematic approach to a common hematologic finding.Curr Hematol Malig Rep. 2021;16(3):267-275. doi:10.1007/s11899-021-00618-4Hirose S, Lin Q, Ohtsuji M, Nishimura H, Verbeek JS.Monocyte subsets involved in the development of systemic lupus erythematosus and rheumatoid arthritis.Int Immunol. 2019 Oct 16;31(11):687-696. doi:10.1093/intimm/dxz036.Kim KY, Shin KY, Chang KA.Potential inflammatory biomarkers for major depressive disorder related to suicidal behaviors: a systematic review.Int J Mol Sci. 2023;24(18):13907. doi:10.3390/ijms241813907Hayley S, Hakim AM, Albert PR.Depression, dementia and immune dysregulation.Brain. 2021;144(3):746–60. doi:10.1093/brain/awaa405Arslanoğlu E, Işık ME, Kara KA, Yigit F, Çine N, Tunçer E, Ceyran H.Preoperative monocytosis is predictable at diagnosis for RT-PCR negative COVİD-19 paediatric cardiac surgery patients.Cardiol Young.2021:1-5. doi:10.1017/S104795112100319XMałujło-Balcerska E, Pietras T.Deiodinase types 1 and 3 and proinflammatory cytokine values may discriminate depressive disorder patients from healthy controls.J Clin Med. 2023;12(19):6163. doi:10.3390/jcm12196163Cleveland Clinic.Monocytes.

Mangaonkar AA, Tande AJ, Bekele DI.Differential diagnosis and workup of monocytosis: A systematic approach to a common hematologic finding.Curr Hematol Malig Rep. 2021;16(3):267-275. doi:10.1007/s11899-021-00618-4

Hirose S, Lin Q, Ohtsuji M, Nishimura H, Verbeek JS.Monocyte subsets involved in the development of systemic lupus erythematosus and rheumatoid arthritis.Int Immunol. 2019 Oct 16;31(11):687-696. doi:10.1093/intimm/dxz036.

Kim KY, Shin KY, Chang KA.Potential inflammatory biomarkers for major depressive disorder related to suicidal behaviors: a systematic review.Int J Mol Sci. 2023;24(18):13907. doi:10.3390/ijms241813907

Hayley S, Hakim AM, Albert PR.Depression, dementia and immune dysregulation.Brain. 2021;144(3):746–60. doi:10.1093/brain/awaa405

Arslanoğlu E, Işık ME, Kara KA, Yigit F, Çine N, Tunçer E, Ceyran H.Preoperative monocytosis is predictable at diagnosis for RT-PCR negative COVİD-19 paediatric cardiac surgery patients.Cardiol Young.2021:1-5. doi:10.1017/S104795112100319X

Małujło-Balcerska E, Pietras T.Deiodinase types 1 and 3 and proinflammatory cytokine values may discriminate depressive disorder patients from healthy controls.J Clin Med. 2023;12(19):6163. doi:10.3390/jcm12196163

Cleveland Clinic.Monocytes.

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