Immunoglobulin M antibodies (IgM) are our first-line defense against a broad range of infections. They are often measured to help diagnose different conditions, such as infections, immunodeficiency, autoimmune disease, and certain types of cancer. Keep reading to learn more about high and low IgM levels and how to improve them.

What is Immunoglobulin M (IgM)?

Antibodies are large proteins of the immune system that neutralize intruders, such as bacteria, viruses, fungi, and parasites. There are five main types of antibodies: IgA, IgD, IgE, IgG, and IgM.

IgM (Immunoglobulin M) are the largest antibodies. They are the first-line defense of our immune system. They provide general but short-term protection against new infections. IgM levels decline as the body starts producing more IgG antibodies, which are responsible for long-term protection against pathogens [1, 2].

Apart from “immune” IgM antibodies, which are produced in response to infections, we also have “natural” IgM antibodies that circulate in the blood without exposure to any intruders (antigens) [1, 3]. These are responsible for removing damaged and pre-cancerous cells, thereby also decreasing inflammation and protecting us from autoimmunity [4, 5, 6].

Normal Range

Antibodies are measured to help diagnose different conditions, such as infections, immunodeficiency, autoimmune disease, and certain types of cancer. Having too few immunoglobulins makes you more susceptible to infections. Having to many, on the other hand, may mean you have an overactive immune system.

The normal range for IgM in the blood is 40 – 230 mg/dL (milligrams per deciliter) [7].

Women normally have higher IgM levels than men [8].

Low Immunoglobulin M

Low levels of IgM mean your immune system is not working optimally. Because this antibody helps provide protection against bacteria and viruses, having low IgM levels is associated with a higher risk of recurring infections [9].

Causes of Low IgM

The following lifestyle choices can decrease IgM levels:

  • Smoking along with alcohol consumption [10]
  • Endurance exercise and overtraining [11, 12]

Further, these diseases and disorders are associated with lower IgM levels:

  • Some autoimmune and inflammatory diseases, such as:
    • Rheumatoid arthritis [13]
    • Hashimoto’s thyroiditis [14]
    • Lupus [15, 14]
    • Celiac disease [16]
    • Crohn’s disease [17, 14]
    • Immune thrombocytopenia [18]
  • Diabetes [19, 20]
  • Selective immunoglobulin M deficiency, a rare and sometimes hereditary disorder [14, 21]
  • Wiskott-Aldrich syndrome, a rare immune deficiency disorder [22]
  • Lymphoid nodular hyperplasia [23]
  • Leukemia [24]

Symptoms of Low IgM

Some people with low IgM levels may not show any symptoms at all. Other people will suffer from recurring infections [14].

Ways to Increase IgM

Refrain from smoking and drinking alcohol. In a study of 1,787 subjects, alcohol or smoking had little effect on IgM in isolation. However, combined with smoking, even low levels of alcohol consumption significantly decreased IgM in the blood [10].

If your IgM levels are low and you are prone to infections, make sure you are not over-training and avoid endurance exercise until your levels recover [11, 12].

The following supplements can help increase IgM levels:

High Immunoglobulin M

There are two types of IgM antibodies: natural and immune [1, 3]. The body produces immune IgM antibodies in response to intruders (antigens). That is why IgM levels tend to increase during the initial phase of infections. IgM levels eventually decline as the body starts producing more IgG antibodies [1].

Doctors often use specific IgM antibodies to diagnose acute infections, such as hepatitis, CMV, EBV, HIV, measles, rubella, and mumps. However, the tests for specific IgM antibodies can be falsely positive — they can be elevated even when there is no disease present. That’s why it is prudent to follow up this test with one or several more reliable tests [32].

Causes of High IgM

IgM levels can be increased due to:

  • Infections [33, 34, 32, 35]. Viral and bacterial infections are the most common causes of high IgM levels.
  • Some autoimmune disorders, including:
  • Kidney damage. In kidney damage proteins such as albumin and IgG are lost through urine (nephrotic syndrome), but IgM in the blood conversely increases [40, 41].
  • Hyper-immunoglobulin M syndromes, a group of genetic immunodeficiency disorders with high IgM and low levels of other immunoglobulins [42, 43]
  • Louis–Bar syndrome (ataxia-telangiectasia), a rare genetic neurodegenerative disease [44]
  • Cancers, such as multiple myeloma and Waldenstrom’s macroglobulinemia (a type of non-Hodgkin’s lymphoma) [45, 46, 47, 48]

Health Effects of High IgM

1) Higher IgM Levels and Metabolic Syndrome

Metabolic syndrome is a condition characterized by three or more of the following conditions: fat around the stomach, high blood pressure, high blood sugar levels, high triglyceride levels, and low HDL-C levels.

In a study of 9,379 people, higher IgM levels (above 110 mg/dL for men and 150 mg/dL for women) were associated with a higher incidence of metabolic syndrome (elevated triglycerides and lower HDL-C in particular) [49].

Similarly, in another study with 460 participants, those with either high triglycerides or low HDL-cholesterol had higher IgM levels [8].

2) High IgM Levels Increase All-Cause Mortality Risk

In a study of 4,255 US army personnel, higher IgM levels were associated with higher all-cause mortality [50]. This is not surprising, as high IgM levels are often due to infectious and autoimmune diseases.

Ways to Decrease IgM

To decrease IgM levels, you need to work on resolving the underlying health issue with a health care professional.

Irregular IgM Levels?

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