Immunoglobulin M (IgM)

Immunoglobulin M (IgM): role, symptoms of deficiency and excess, blood standards

1. The role of IgM in the body

Immunoglobulin M (IgM) is the first antibody produced by the immune system in response to an infection. They play a key role in the primary immune response.

Main functions:
✔ First line of defense:

• They appear first when they encounter a pathogen (5-7 days after infection)
• Effectively activate the complement system
• Cause agglutination (gluing) of bacteria

✔ Structural features:

• Large pentameric molecules (10 antigen-binding sites)
• Do not pass through the placenta (diagnostic marker of intrauterine infections)

✔ Protective mechanisms:

• Virus neutralization
• Opsonization of bacteria
• Activation of inflammatory responses

2. Symptoms of IgM deficiency

Reasons:

• Congenital immunodeficiency (Bruton’s agammaglobulinemia, selective IgM deficiency)
• Acquired conditions (lymphoproliferative diseases, nephrotic syndrome)

Clinical manifestations:

• Severe bacterial infections (meningitis, sepsis)
• Hypersensitivity to viral infections
• Chronic gastroenteritis
• Autoimmune complications

3. Symptoms of excess IgM

Reasons:

• Acute infections (bacterial, viral, parasitic)
• Autoimmune diseases (rheumatoid arthritis, SLE)
• Waldenstrom’s macroglobulinemia
• Chronic liver diseases

Clinical manifestations:

• With macroglobulinemia:
• Hyperviscosity syndrome (headaches, bleeding)
• Lymphadenopathy
• Hepatosplenomegaly
• For infections:
• Fever
• General intoxication

4. IgM standards in the blood test

Age group	Reference values (g/L)
Newborns	0.06–0.21
1–3 months	0.17–0.66
4–6 months	0.26–0.82
7–12 months	0.36–1.00
1–3 years	0.45–1.20
4–6 years	0.50–1.60
7–9 years	0.55–1.70
10–11 years	0.60–1.80
12–13 years	0.65–1.85
Adults	0.40–2.30

Interpretation features:

• Adult levels are reached by 12-14 years of age
• Increase in pregnancy (physiological)
• Daily fluctuations up to 15%

5. Diagnostic value

An increase in IgM indicates:

• Acute infection (especially useful for diagnosing TORCH infections)
• Exacerbation of a chronic disease
• Autoimmune processes

A decrease in IgM is observed when:

• Primary immunodeficiency disorders
• Lymphoproliferative diseases
• Conditions after splenectomy

6. When is the test scheduled?

• Diagnosis of acute infections
• Assessment of immune status
• Diagnosis of intrauterine infections
• Suspected macroglobulinemia
• Control of autoimmune diseases

7. Additional research

• Electrophoresis of serum proteinsProteins are high-molecular organic substances consisting of alpha-amino acids linked in a chain by a peptide bond. In living organisms, the amino acid composition of proteins is determined by the genetic code. During synthesis, 20 standard amino acids are used in most cases. Many combinations of them determine the great diversity of properties of protein molecules. Proteins play a key role in the immune response and can perform transport, storage, catalytic, structural, and receptor functions. Proteins are an important part of the nutrition of animals and humans. The main sources of proteins are meat, poultry, fish, milk, nuts, legumes, and grains.
• Immunofixation
• Determination of specific IgMs
• Evaluation of other immunoglobulins (IgG, IgA)

8. Treatment approach

If there is a shortage:

• Infection prevention
• Immunoglobulin replacement therapy
• Treatment of concomitant diseases

If there is an excess:

• For macroglobulinemia-chemotherapy
• For hyperviscosity syndrome-plasmapheresis
• Treatment of the underlying disease