Monocytosis: Causes, Definition & Treatment (2023)


What is monocytosis?

If you have monocytosis, it means you have an abnormally high number of infection-fighting monocytes. Monocytes are a specific type of white blood cell that protects your immune system from toxic or foreign substances. A high monocyte count doesn’t necessarily mean you have a serious medical condition. If you have monocytosis, your healthcare provider will take a close look at your overall health so they can identify and treat any underlying cause.

Symptoms and Causes

What causes monocytosis?

A high monocyte count is a potential sign of many different medical conditions. It’s often linked to infectious diseases like mononucleosis or an autoimmune disease like lupus. Some medications can cause monocytosis. It’s also linked to conditions such as blood disorders and certain cancers.

(Video) Monocytosis | High Monocyte Count | Types, Causes, Symptoms, Treatment Of Monocytopenia |

But you can develop a high monocyte count for reasons that are less serious. For example, chronic stress or challenging workouts can cause monocytosis. Pregnancy can also cause monocytosis.

A monocytosis diagnosis is often the very first step toward a final diagnosis.

What are the symptoms?

Monocytosis doesn’t usually cause symptoms. Instead, you may have symptoms of the medical condition that caused your high monocyte count.

Diagnosis and Tests

How do healthcare providers diagnose monocytosis?

Sometimes your provider discovers you have monocytosis as a result of a routine blood test. Since this may be a sign of many potential medical conditions, your provider will perform several more tests:

  • Complete blood count (CBC): This test is an initial step toward finding out why you have monocytosis. Your provider takes a sample of your blood so they can count the number of blood cells in your sample. Monocytes are a type of white blood cell, so your provider may also analyze the number of other types of white blood cell types in your sample.
  • Peripheral blood smear. This test helps your provider narrow down the list of potential problems. Your provider examines a sample of your blood under a microscope to assess your cells’ size and shape.
  • Absolute monocyte count: This test shows the number of monocytes in your blood sample. An absolute monocyte count is based on multiplying the percentage of monocytes in your CBC by the total number of white blood cells. Your provider uses this test result to find out whether your monocyte count is normal, too high or too low.

Your provider may also check your spleen, liver and lymph nodes to see if they are larger than normal. Depending on the preliminary findings, your provider may recommend other tests to help them identify what caused your monocytosis.

(Video) What is Monocytosis? and its Causes and Treatment ........

Management and Treatment

How do healthcare providers treat monocytosis?

Providers treat the underlying condition that caused you to have a high monocyte count.

(Video) What is the most common cause of high monocytes?


Can I prevent monocytosis?

Monocytosis is a sign of an underlying infection or other condition. Given that, the best way to prevent monocytosis is avoid infections, manage any current medical conditions and boost your immune system. Here are some other suggestions:

  • Eat a well-balanced diet that limits foods that cause inflammation like red meats, fried foods and refined carbohydrates.
  • Try to get regular exercise.
  • Try to stay well-rested.
  • If you drink alcohol, use moderation.
  • If you smoke or use tobacco products, try to quit.
  • Reduce stress.
  • Protect yourself against infections. Avoid people who are ill and wash your hands often.

Outlook / Prognosis

What can I expect if I have monocytosis?

A high monocyte count is a sign of several medical conditions that are treated in different ways. Once you and your provider know the underlying cause, you’ll have a better idea of how your condition may affect your daily life.

(Video) What are the symptoms of high monocytes?

Living With

When should I see my healthcare provider?

Lots of medical conditions can cause high monocyte counts. If you’re being treated for one of these medical conditions, you’ll probably have regular appointments so your provider can diagnose and treat the underlying condition.

When should I go to the emergency room?

If you have a medical condition linked to monocytosis, you should go to the emergency room if your symptoms get worse, you have new symptoms or your reaction to treatment is more than you anticipated.

What questions should I ask my doctor?

Being diagnosed with monocytosis may be the first time you realize you may have a medical condition. Or you may already be dealing with the condition. Either way, you may have questions for your healthcare provider. Here are a few questions to consider:

(Video) What does Monocytosis indicate?

  • What is monocytosis?
  • Why do I have monocytosis?
  • Does this mean I have a serious medical condition?
  • How do you find out what caused my monocytosis?
  • How soon will I know what’s wrong with me?
  • I know I have a medical condition that causes my high monocyte count. Does a high count mean my condition is getting worse?

A note from Cleveland Clinic

Monocytosis may be a sign you have a serious medical condition such as an autoimmune disease, a blood disorder, cancer or cardiovascular disease. It may mean you have an infection. It may mean you’ve been under stress or are recovering from an infection. You won’t know what it means until your provider can identify the underlying cause. Try to remember that there’s a big difference between signs, symptoms and a final diagnosis. Ask your healthcare provider to explain the diagnostic process so you know what to expect.


What is monocytosis cause? ›

Monocytosis happens when your monocyte count is too high. Monocytosis is often linked to infectious diseases and autoimmune diseases. It's also linked to blood disorders and certain cancers. But being diagnosed with monocytosis doesn't mean you have a serious medical condition.

What is the treatment for monocytosis? ›

Monocytosis itself is only a symptom and doesn't require treatment. Treating the underlying cause will resolve the monocytosis. A high monocyte count can have a wide range of causes. Your doctor may do additional tests to help determine the cause of your monocytosis.

What is the most common cause of high monocytes? ›

Monocytosis occurs when your monocyte count is too high. It's most often linked to a chronic infection or disease that your body is fighting. Causes of monocytosis include: Autoimmune diseases (lupus, rheumatoid arthritis).

What medications cause monocytosis? ›

Monocytosis may be seen in patients receiving cytokines (GM-CSF, M-CSF) TNF-alpha or drugs that increase levels of IL- 3, IL-6, or IL-1. It has also been described in patients taking Olanzapine, allopurinol, corticosteroids, and Griseofulvin.

What causes monocytosis in adults? ›

  • Infections: tuberculosis, brucellosis, listeriosis, subacute bacterial endocarditis, syphilis, and other viral infections and many protozoal and rickettsial infections (e.g. kala azar, malaria, Rocky Mountain spotted fever).
  • Blood and immune causes: chronic neutropenia and myeloproliferative disorders.

What infections cause high monocytes? ›

What are the risk factors for a high monocyte level?
  • viral infections, such as infectious mononucleosis, mumps, and measles.
  • parasitic infections.
  • bacterial infections, including TB.
  • chronic inflammatory disease.
  • autoimmune diseases , such as rheumatoid arthritis, inflammatory bowel disease (IBD), and celiac disease.

Can high monocytes be treated? ›

If you have a high monocyte count, it's likely due to an infection or another medical cause. If your monocytes are elevated due to an infection, they will get back to normal levels when the infection resolves. If they are elevated due to a medical condition, you would need medical treatment.

What are the side effects of monocytosis? ›

Common symptoms reported by people with monocytosis
  • 1 a monocytosis patient reports severe fatigue (33%)
  • 1 a monocytosis patient reports moderate fatigue (33%)
  • 1 a monocytosis patient reports mild fatigue (33%)
  • 0 monocytosis patients report no fatigue (0%)

Can stress cause high monocytes? ›

Stress-induced brain-to-immune activation leads to enhanced myelopoiesis and monocyte trafficking. SNS and HPA activation following stress exposure significantly shifts immune responses through increased myelopoiesis mediated by increased GM-CSF and reduced CXCL12 expression.

What deficiency causes high monocytes? ›

Conclusions: Vitamin D deficiency is associated with greater inflammation and activated monocyte phenotypes. The role of vitamin D deficiency in persistent immune activation and associated complications during chronic HIV disease should be further evaluated as a possible target for intervention.

What diseases are associated with monocytes? ›

Recent scientific evidence suggests that monocytes not only play a crucial role in our innate immune system by defending the host from intruding microbial pathogens but they also contribute to the pathogenesis and progression of diseases such as liver fibrosis, atherosclerosis, multiple sclerosis, and tumor metastasis.

What cancers cause high monocytes? ›

The most common sign of chronic myelomonocytic leukemia (CMML) is having too many monocytes (seen on a blood test). Having too many monocytes also causes many of the symptoms of CMML. These monocytes can settle in the spleen or liver, enlarging these organs.

What autoimmune disorders cause high monocytes? ›

Accumulating evidence showed that monocyte activation is associated with the disease progression in autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). However, it remains to be determined how monocytes contribute to the disease process and which subset is involved.

What level of monocytes indicate leukemia? ›

Features of chronic myelomonocytic leukemia

People with CMML may have shortages of some blood cells, but a main problem is too many monocytes. (at least 1,000 per mm3). Often, the monocyte count is much higher, causing their total white blood cell count to become very high as well.

Can arthritis cause high monocytes? ›

Monocyte activation is elevated in women with knee-osteoarthritis and associated with inflammation, BMI and pain. Osteoarthritis Cartilage.

When should I be concerned about high monocytes? ›

A monocyte count above 10% is considered high and a cause for concern. When your monocyte count passes this threshold, you have monocytosis. This could result from your immune system fighting something in your body. Read more about monocytosis here.

Do monocytes cause inflammation? ›

They produce effector molecules such as cytokines, myeloperoxidase and superoxide, and initiate inflammation [1]. Inflammatory monocytes selectively traffic to the sites of inflammation, produce inflammatory cytokines and contribute to local and systemic inflammation [2].

Can inflammation increase monocytes? ›

During inflammation, monocytes circulate through the blood and extravasate into inflamed tissues after the general paradigm of the leukocyte recruitment cascade, involving rolling, adhesion, and transmigration. Whether it be an infection or sterile injury, monocyte recruitment is a key feature.

What is an alarming monocyte count? ›

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.

Can lack of sleep increase monocytes? ›

also observed that 64 hours of sleep deprivation increased neutrophil and monocyte counts.

Can liver damage cause high monocytes? ›

Following liver damage in acute liver failure, the absolute number of KCs decreases whereas the liver-recruited monocytes and MoMFs significantly increase as described above (52, 53, 57, 59, 60, 65, 66).

Can iron deficiency cause high monocytes? ›

The study found no significant alteration in the percentages and absolute number of monocytes in iron deficiency as compared to healthy population (p = 0.74, 0.75, respectively).

Can vitamins increase monocytes? ›

Very early research suggests that garlic and supplementing with vitamin C, D, and B12 may be beneficial. Remember these are general recommendations for improving your immune health that may increase your monocyte count.

Does vitamin D reduce inflammation? ›

It has been confirmed that vitamin D has potent anti-inflammatory properties. It contributes to reduction in pro-inflammatory mediators and an increase in anti-inflammatory cytokines. There is also evidence that vitamin D could decrease C-reactive protein (CRP) and affect selected haematological indices.

Does monocytosis mean leukemia? ›

Monocytosis is occasionally a sign of an acute bacterial, viral, protozoal, or rickettsial infection and may also occur in some forms of chronic neutropenia and postsplenectomy states. Chronic inflammatory conditions can stimulate sustained monocytosis, as can preleukemia, chronic myelogenous leukemia, and lymphomas.

Can a virus cause high monocytes? ›

Viral infection triggers rapid differentiation of human blood monocytes into dendritic cells - PMC. The . gov means it's official.

What are signs of leukemia in blood work? ›

Your doctor will conduct a complete blood count (CBC) to determine if you have leukemia. This test may reveal if you have leukemic cells. Abnormal levels of white blood cells and abnormally low red blood cell or platelet counts can also indicate leukemia.

Can thyroid cause high monocytes? ›

Thyroid-stimulating hormone acutely increases monocyte gene expression in vivo.

What are monocytes a marker of? ›

Intermediate Monocytes

They are suspected to play an important role in antigen presentation and rapid pathogen defense, as they been found in increased levels in patients with systemic infections, such as HIV. Human intermediate monocytes have been reported to express the markers CCR2, CCR5, HLA-DR, CD86, and CD11c.

What is the white blood cell count for leukemia? ›

Typically a healthy person has a white blood cell count of about 4,000-11,000. Patients with acute or even chronic leukemia may come in with a white blood cell count up into the 100,000-400,000 range.

How high are monocytes in lymphoma? ›

Nonetheless, the monocyte-to-lymphocyte ratio was significantly higher in the lymphoma group (median, 0.36; IQR, 0.24–0.73) than in the non-lymphoma group (median, 0.29; IQR, 0.21–0.43; P = 0.022), independent of lymph node diameter ≥ 1 cm and C-reactive protein levels.

What are the symptoms of high monocytes? ›

Having too many monocytes also causes many of the symptoms of CMML. These monocytes can settle in the spleen or liver, enlarging these organs. An enlarged spleen (called splenomegaly) can cause pain in the upper left part of the belly (abdomen). It can also cause people to notice they feel full too fast when they eat.

What cancers have high monocytes? ›

Chronic myelomonocytic leukaemia (CMML) is a rare type of blood cancer. In CMML there are too many monocytes in the blood. Monocytes are a type of white blood cell. The World Health Organisation (WHO) has included CMML in a group of blood cancers called myeloproliferative and myelodysplastic disorders.

How can you tell if you have leukemia on a CBC? ›

Leukemia is most often diagnosed through a diagnostic test called a complete blood count (CBC). If a patient's CBC shows abnormal levels of white blood cells or abnormally low red blood cells or platelets, he or she has leukemia. The physician will then order a bone marrow biopsy to determine the type of leukemia.

What would CBC show for leukemia? ›

Complete blood count (CBC): This blood test lets your healthcare provider know if you have abnormal levels of red blood cells, white blood cells and platelets. If you have leukemia, you'll likely have higher than normal counts of white blood cells.


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