Part of
Infection & inflammation
Part of
Infection & inflammation
Blood biomarker
Part of
Infection & inflammation
Immunoglobulin G (IgG)
Immunoglobulin G (IgG)
Immunoglobulin G (IgG) is the most common antibody in blood, crucial for long-term immunity.
Immunoglobulin G (IgG) is the most common antibody in blood, crucial for long-term immunity.
Immunoglobulin G (IgG)
Normal range
Normal range
6-16 g/L
6-16 g/L
Normal range
6-16 g/L
6-16 g/L
Normal range
Immunoglobulin G (IgG)
Immunoglobulin G (IgG)
Immunoglobulin G (IgG) is the most common antibody in blood, crucial for long-term immunity.
Immunoglobulin G (IgG)
Normal range
6-16 g/L
Normal range
6-16 g/L
6-16 g/L
Normal range
Immunoglobulin G (IgG)
Immunoglobulin G (IgG)
Immunoglobulin G (IgG) is the most common antibody in blood, crucial for long-term immunity.
Immunoglobulin G (IgG)
Normal range
6-16 g/L
Normal range
6-16 g/L
6-16 g/L
Normal range
Immunoglobulin G (IgG)
Dr. Jack Devin
MBBS
Your Body's Long-Term Immunity Champion
Your Body's Long-Term Immunity Champion
IgG is your immune system's memory keeper and primary defender, making up about 75% of all antibodies circulating in your bloodstream. This powerhouse antibody provides long-lasting protection against infections you've encountered before, whether through illness or vaccination. Unlike other antibodies that work at specific sites, IgG travels throughout your entire body via the bloodstream, crossing tissue barriers and even passing from mother to baby during pregnancy to provide crucial early protection. When IgG levels are balanced, you enjoy robust immunity and effective responses to both new and familiar threats. But when they're disrupted, your body's ability to fight infections and maintain immune memory becomes compromised.
IgG is your immune system's memory keeper and primary defender, making up about 75% of all antibodies circulating in your bloodstream. This powerhouse antibody provides long-lasting protection against infections you've encountered before, whether through illness or vaccination. Unlike other antibodies that work at specific sites, IgG travels throughout your entire body via the bloodstream, crossing tissue barriers and even passing from mother to baby during pregnancy to provide crucial early protection. When IgG levels are balanced, you enjoy robust immunity and effective responses to both new and familiar threats. But when they're disrupted, your body's ability to fight infections and maintain immune memory becomes compromised.
When IgG Levels Are Too Low
When IgG Levels Are Too Low
When IgG Levels Are Too Low
Understand how insufficient IgG leaves you vulnerable to recurrent infections and why your immune system struggles to remember past encounters.
Read more
When IgG Levels Are Too High
When IgG Levels Are Too High
When IgG Levels Are Too High
Discover why elevated IgG often signals chronic immune activation, autoimmune disease, or persistent infection.
Read more
What Influences Your IgA Levels?
What Influences Your IgA Levels?
What Influences Your IgA Levels?
From infections and medications to genetic factors, learn what can strengthen or weaken your body's primary immune defence.
Read more
Understanding Your Results
Understanding Your Results
Understanding Your Results
Decode your blood test numbers and know what your IgG levels reveal about your immune system's strength and memory.
Read more
When IgG Levels Are Too Low
Transiently low or borderline IgA levels are not likely to be clinically significant.
Significantly low IgG levels, known as hypogammaglobulinaemia, significantly weaken your body’s ability to fight infections and maintain immunological memory. This condition leaves you particularly vulnerable to bacterial infections, as IgG is your primary defense against encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
With insufficient IgG circulating in your system, your immune system struggles to recognize and respond effectively to pathogens you’ve encountered before, leading to recurrent, sometimes severe infections.
Common symptoms include frequent respiratory tract infections such as sinusitis, pneumonia, or bronchitis that keep returning, recurrent gastrointestinal infections leading to chronic diarrhoea or digestive problems, skin and soft tissue infections that heal slowly or recur frequently, unusual susceptibility to bacterial infections that others might easily fight off, and prolonged recovery times from any illness.
Many people with low IgG describe feeling constantly “run down.” In severe cases, chronic lung damage from repeated infections or life‑threatening systemic infections can occur.
When IgG Levels Are Too Low
Transiently low or borderline IgA levels are not likely to be clinically significant.
Significantly low IgG levels, known as hypogammaglobulinaemia, significantly weaken your body’s ability to fight infections and maintain immunological memory. This condition leaves you particularly vulnerable to bacterial infections, as IgG is your primary defense against encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
With insufficient IgG circulating in your system, your immune system struggles to recognize and respond effectively to pathogens you’ve encountered before, leading to recurrent, sometimes severe infections.
Common symptoms include frequent respiratory tract infections such as sinusitis, pneumonia, or bronchitis that keep returning, recurrent gastrointestinal infections leading to chronic diarrhoea or digestive problems, skin and soft tissue infections that heal slowly or recur frequently, unusual susceptibility to bacterial infections that others might easily fight off, and prolonged recovery times from any illness.
Many people with low IgG describe feeling constantly “run down.” In severe cases, chronic lung damage from repeated infections or life‑threatening systemic infections can occur.
When IgG Levels Are Too Low
Transiently low or borderline IgA levels are not likely to be clinically significant.
Significantly low IgG levels, known as hypogammaglobulinaemia, significantly weaken your body’s ability to fight infections and maintain immunological memory. This condition leaves you particularly vulnerable to bacterial infections, as IgG is your primary defense against encapsulated bacteria like Streptococcus pneumoniae and Haemophilus influenzae.
With insufficient IgG circulating in your system, your immune system struggles to recognize and respond effectively to pathogens you’ve encountered before, leading to recurrent, sometimes severe infections.
Common symptoms include frequent respiratory tract infections such as sinusitis, pneumonia, or bronchitis that keep returning, recurrent gastrointestinal infections leading to chronic diarrhoea or digestive problems, skin and soft tissue infections that heal slowly or recur frequently, unusual susceptibility to bacterial infections that others might easily fight off, and prolonged recovery times from any illness.
Many people with low IgG describe feeling constantly “run down.” In severe cases, chronic lung damage from repeated infections or life‑threatening systemic infections can occur.
When IgG Levels Are Too High
Elevated IgG levels typically indicate chronic immune system activation, often in response to persistent infection, autoimmune disease, or chronic inflammation. Unlike IgG deficiency, high levels usually reflect an overactive rather than underactive immune response.
High IgG levels commonly occur in response to chronic infections where your immune system is working overtime to control persistent pathogens, autoimmune conditions where your immune system mistakenly attacks your own tissues, chronic liver disease which can stimulate antibody production, certain blood disorders that affect antibody-producing cells, and chronic inflammatory conditions that keep your immune system in a heightened state.
Symptoms associated with elevated IgG often relate to the underlying condition rather than the high antibody levels themselves. These might include joint pain, stiffness, unexplained fevers or night sweats.
When IgG Levels Are Too High
Elevated IgG levels typically indicate chronic immune system activation, often in response to persistent infection, autoimmune disease, or chronic inflammation. Unlike IgG deficiency, high levels usually reflect an overactive rather than underactive immune response.
High IgG levels commonly occur in response to chronic infections where your immune system is working overtime to control persistent pathogens, autoimmune conditions where your immune system mistakenly attacks your own tissues, chronic liver disease which can stimulate antibody production, certain blood disorders that affect antibody-producing cells, and chronic inflammatory conditions that keep your immune system in a heightened state.
Symptoms associated with elevated IgG often relate to the underlying condition rather than the high antibody levels themselves. These might include joint pain, stiffness, unexplained fevers or night sweats.
When IgG Levels Are Too High
Elevated IgG levels typically indicate chronic immune system activation, often in response to persistent infection, autoimmune disease, or chronic inflammation. Unlike IgG deficiency, high levels usually reflect an overactive rather than underactive immune response.
High IgG levels commonly occur in response to chronic infections where your immune system is working overtime to control persistent pathogens, autoimmune conditions where your immune system mistakenly attacks your own tissues, chronic liver disease which can stimulate antibody production, certain blood disorders that affect antibody-producing cells, and chronic inflammatory conditions that keep your immune system in a heightened state.
Symptoms associated with elevated IgG often relate to the underlying condition rather than the high antibody levels themselves. These might include joint pain, stiffness, unexplained fevers or night sweats.
What Influences Your IgG Levels?
Factors That Can Lower IgG
Primary immunodeficiencies (e.g., Common Variable Immunodeficiency)
Medications: immunosuppressants, chemotherapy, long‑term corticosteroids
Protein‑losing conditions: nephrotic syndrome, severe burns, gastrointestinal protein loss
Chronic kidney or liver disease
Malnutrition or severe protein deficiency
Age‑related decline (levels are lower in infants and gradually rise to adult norms)
Certain genetic conditions affecting antibody production
Factors That Can Raise IgG
Persistent infections (bacterial, viral, parasitic)
Autoimmune diseases (such as lupus or rheumatoid arthritis
Chronic liver disease, especially autoimmune hepatitis
Certain blood cancers including multiple myeloma or lymphoma
Recent vaccinations or acute infections can cause temporary rises
Chronic inflammatory bowel disease
Some medications that stimulate immune responses
Usually the results are interpreted in the context of a full blood count and comprehensive health check, so borderline or clinically insignificant changes to IgG can be distinguished from more clinically concerning results.
What Influences Your IgG Levels?
Factors That Can Lower IgG
Primary immunodeficiencies (e.g., Common Variable Immunodeficiency)
Medications: immunosuppressants, chemotherapy, long‑term corticosteroids
Protein‑losing conditions: nephrotic syndrome, severe burns, gastrointestinal protein loss
Chronic kidney or liver disease
Malnutrition or severe protein deficiency
Age‑related decline (levels are lower in infants and gradually rise to adult norms)
Certain genetic conditions affecting antibody production
Factors That Can Raise IgG
Persistent infections (bacterial, viral, parasitic)
Autoimmune diseases (such as lupus or rheumatoid arthritis
Chronic liver disease, especially autoimmune hepatitis
Certain blood cancers including multiple myeloma or lymphoma
Recent vaccinations or acute infections can cause temporary rises
Chronic inflammatory bowel disease
Some medications that stimulate immune responses
Usually the results are interpreted in the context of a full blood count and comprehensive health check, so borderline or clinically insignificant changes to IgG can be distinguished from more clinically concerning results.
What Influences Your IgG Levels?
Factors That Can Lower IgG
Primary immunodeficiencies (e.g., Common Variable Immunodeficiency)
Medications: immunosuppressants, chemotherapy, long‑term corticosteroids
Protein‑losing conditions: nephrotic syndrome, severe burns, gastrointestinal protein loss
Chronic kidney or liver disease
Malnutrition or severe protein deficiency
Age‑related decline (levels are lower in infants and gradually rise to adult norms)
Certain genetic conditions affecting antibody production
Factors That Can Raise IgG
Persistent infections (bacterial, viral, parasitic)
Autoimmune diseases (such as lupus or rheumatoid arthritis
Chronic liver disease, especially autoimmune hepatitis
Certain blood cancers including multiple myeloma or lymphoma
Recent vaccinations or acute infections can cause temporary rises
Chronic inflammatory bowel disease
Some medications that stimulate immune responses
Usually the results are interpreted in the context of a full blood count and comprehensive health check, so borderline or clinically insignificant changes to IgG can be distinguished from more clinically concerning results.
Understanding Your Results
IgG levels are measured in grams per litre (g/L) in serum for adults:
Low: <7.0 g/L
Normal: 7.0–16.0 g/L
High: >16.0 g/L
Your IgG results should be interpreted alongside your clinical symptoms, infection history, and other immune markers. It's important to consider that IgG levels can fluctuate based on recent infections, vaccinations, or changes in your overall health status. Your healthcare provider may recommend repeat testing or additional immune function tests to get a complete picture.
Understanding Your Results
IgG levels are measured in grams per litre (g/L) in serum for adults:
Low: <7.0 g/L
Normal: 7.0–16.0 g/L
High: >16.0 g/L
Your IgG results should be interpreted alongside your clinical symptoms, infection history, and other immune markers. It's important to consider that IgG levels can fluctuate based on recent infections, vaccinations, or changes in your overall health status. Your healthcare provider may recommend repeat testing or additional immune function tests to get a complete picture.
Understanding Your Results
IgG levels are measured in grams per litre (g/L) in serum for adults:
Low: <7.0 g/L
Normal: 7.0–16.0 g/L
High: >16.0 g/L
Your IgG results should be interpreted alongside your clinical symptoms, infection history, and other immune markers. It's important to consider that IgG levels can fluctuate based on recent infections, vaccinations, or changes in your overall health status. Your healthcare provider may recommend repeat testing or additional immune function tests to get a complete picture.
The Takeaway
Immunoglobulin G is your immune system's backbone, providing lasting protection against infections and maintaining immunological memory of past encounters with pathogens. Healthy IgG levels are essential for effective immune responses and long-term protection against disease.
Low IgG raises your risk for severe or recurrent infections and may indicate immunodeficiency. High IgG may point to chronic infection, autoimmunity, or blood disorders.
The positive news is that IgG-related immune problems are often manageable with appropriate treatment. If your IgG levels are significantly abnormal, working with your healthcare provider to identify the cause and develop an appropriate treatment plan can help restore your immune balance and protect your long-term health.
The Takeaway
Immunoglobulin G is your immune system's backbone, providing lasting protection against infections and maintaining immunological memory of past encounters with pathogens. Healthy IgG levels are essential for effective immune responses and long-term protection against disease.
Low IgG raises your risk for severe or recurrent infections and may indicate immunodeficiency. High IgG may point to chronic infection, autoimmunity, or blood disorders.
The positive news is that IgG-related immune problems are often manageable with appropriate treatment. If your IgG levels are significantly abnormal, working with your healthcare provider to identify the cause and develop an appropriate treatment plan can help restore your immune balance and protect your long-term health.
The Takeaway
Immunoglobulin G is your immune system's backbone, providing lasting protection against infections and maintaining immunological memory of past encounters with pathogens. Healthy IgG levels are essential for effective immune responses and long-term protection against disease.
Low IgG raises your risk for severe or recurrent infections and may indicate immunodeficiency. High IgG may point to chronic infection, autoimmunity, or blood disorders.
The positive news is that IgG-related immune problems are often manageable with appropriate treatment. If your IgG levels are significantly abnormal, working with your healthcare provider to identify the cause and develop an appropriate treatment plan can help restore your immune balance and protect your long-term health.
References
Orange, J. S., Ballow, M., Stiehm, E. R., et al. (2006). Use and interpretation of diagnostic vaccination in primary immunodeficiency. Journal of Allergy and Clinical Immunology, 117(6), 1391-1398.
Bonilla, F. A., Khan, D. A., Ballas, Z. K., et al. (2015). Practice parameter for the diagnosis and management of primary immunodeficiency. Journal of Allergy and Clinical Immunology, 136(5), 1186-1205.
Dispenzieri, A., Gertz, M. A., Therneau, T. M., et al. (2001). Retrospective cohort study of 148 patients with polyclonal gammopathy. Mayo Clinic Proceedings, 76(5), 476-487.
British Society for Immunology. (2019). Clinical Guidelines for Immunoglobulin Use. Second Edition Update.
UK Primary Immunodeficiency Network. (2020). Guidelines for the clinical management of common variable immunodeficiency disorders.
References
Orange, J. S., Ballow, M., Stiehm, E. R., et al. (2006). Use and interpretation of diagnostic vaccination in primary immunodeficiency. Journal of Allergy and Clinical Immunology, 117(6), 1391-1398.
Bonilla, F. A., Khan, D. A., Ballas, Z. K., et al. (2015). Practice parameter for the diagnosis and management of primary immunodeficiency. Journal of Allergy and Clinical Immunology, 136(5), 1186-1205.
Dispenzieri, A., Gertz, M. A., Therneau, T. M., et al. (2001). Retrospective cohort study of 148 patients with polyclonal gammopathy. Mayo Clinic Proceedings, 76(5), 476-487.
British Society for Immunology. (2019). Clinical Guidelines for Immunoglobulin Use. Second Edition Update.
UK Primary Immunodeficiency Network. (2020). Guidelines for the clinical management of common variable immunodeficiency disorders.
References
Orange, J. S., Ballow, M., Stiehm, E. R., et al. (2006). Use and interpretation of diagnostic vaccination in primary immunodeficiency. Journal of Allergy and Clinical Immunology, 117(6), 1391-1398.
Bonilla, F. A., Khan, D. A., Ballas, Z. K., et al. (2015). Practice parameter for the diagnosis and management of primary immunodeficiency. Journal of Allergy and Clinical Immunology, 136(5), 1186-1205.
Dispenzieri, A., Gertz, M. A., Therneau, T. M., et al. (2001). Retrospective cohort study of 148 patients with polyclonal gammopathy. Mayo Clinic Proceedings, 76(5), 476-487.
British Society for Immunology. (2019). Clinical Guidelines for Immunoglobulin Use. Second Edition Update.
UK Primary Immunodeficiency Network. (2020). Guidelines for the clinical management of common variable immunodeficiency disorders.
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