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. It’s simply an indication of potential trouble.


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.


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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.

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.

Management and Treatment

How do healthcare providers treat monocytosis?

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



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.

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:

  • 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.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 04/12/2022.

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