The immune system relies on immunoglobulins to defend the body against infections. Immunoglobulin G (IgG) is the most abundant antibody in the blood and helps neutralize harmful bacteria, viruses, and other pathogens. When IgG levels drop, the body becomes more vulnerable to infections, leading to increased illness and complications. Among the possible causes, autoimmune diseases play a significant role in affecting IgG levels.
What is Low IgG?
Low IgG means the immune system is not producing enough antibodies to fight infections effectively. This can lead to frequent infections, slow recovery, and increased risk of complications. Blood tests help determine if a person has low total IgG and classify its severity.
The impact of low IgG varies depending on the underlying cause. Some people experience mild symptoms, while others suffer from recurrent, severe infections requiring ongoing treatment.
What Autoimmune Diseases Cause Low IgG?
Certain autoimmune diseases disrupt the immune system’s ability to produce antibodies, leading to low IgG levels. Some of the most well-known conditions associated with IgG deficiency include:
- Common Variable Immunodeficiency (CVID) – A disorder where the immune system fails to produce enough IgG, making individuals prone to infections.
- Systemic Lupus Erythematosus (SLE) – This autoimmune disease can lower IgG levels due to immune system dysfunction.
- Rheumatoid Arthritis (RA) – Some RA patients develop low IgG as a result of immune system irregularities or treatment side effects.
- Sjogren’s Syndrome – This condition can interfere with antibody production, leading to IgG deficiencies.
- Multiple Myeloma – A cancer that affects B-cells, which are responsible for producing immunoglobulins, including IgG.
These autoimmune diseases cause low IgG by either directly damaging immune cells or altering the immune response, making antibody production inefficient.
IgG Subclass Deficiency and Autoimmune Disease
IgG consists of four subclasses: IgG1, IgG2, IgG3, and IgG4. Each subclass plays a specific role in immune defense. Some individuals experience a deficiency in one or more IgG subclasses, even if their total IgG levels appear normal. This condition is called IgG subclass deficiency.
Autoimmune diseases can trigger IgG subclass deficiencies, affecting the immune system’s ability to function properly. For example:
- IgG2 Low Levels – Often associated with autoimmune diseases like lupus and rheumatoid arthritis, IgG2 deficiency can make individuals prone to respiratory infections.
- IgG3 Deficiency – This subtype plays a crucial role in fighting viral infections. A deficiency can lead to chronic infections and has been linked to autoimmune conditions.
IgG subclass deficiencies may not always cause noticeable symptoms, but they can increase the risk of infections and autoimmune complications.
Other Causes of Low IgG
Autoimmune diseases are not the only reason for low IgG. Certain medications, such as immunosuppressants, corticosteroids, chemotherapy, and some anti-seizure drugs, can reduce IgG production.
Infections like HIV directly weaken the immune system, leading to lower IgG levels. Chronic infections can also wear down the body’s ability to produce antibodies over time.
Medical conditions such as nephrotic syndrome and protein-losing enteropathy cause excessive protein loss, including immunoglobulins, making the immune system weaker.
Some genetic disorders, including X-linked agammaglobulinemia (XLA) and transient hypogammaglobulinemia of infancy (THI), lead to low IgG from birth. These conditions often require lifelong monitoring.
Aging also plays a role in declining IgG levels. As the immune system weakens with age, older adults become more susceptible to infections. Regular health checkups and vaccinations help reduce this risk.
Diagnosing and Monitoring Low IgG Levels
A doctor diagnoses low IgG levels through blood tests that measure total IgG and its subclasses. These tests help determine whether a person has hypogammaglobulinemia or an IgG subclass deficiency.
Diagnosis involves:
- Evaluating medical history to check for recurrent infections or autoimmune conditions
- Conducting blood tests to measure IgG levels
- Performing additional tests to identify underlying causes, such as genetic disorders or cancer
Identifying the root cause of IgG deficiency is essential for creating an effective treatment plan.
Treatment Options for Low IgG
Managing low IgG depends on its severity and underlying cause. Some cases require only monitoring, while others need long-term treatment.
Common treatment approaches include:
- Antibiotics – To prevent and treat infections caused by low IgG.
- Immunoglobulin Replacement Therapy (IgG Therapy) – Used for individuals with severe deficiencies, this treatment provides antibodies from healthy donors.
- Addressing Underlying Conditions – If an autoimmune disease is causing IgG deficiency, doctors focus on treating that condition.
Potential Complications of Low IgG
Without proper management, IgG deficiencies can lead to severe infections and long-term health complications. Some potential risks include:
- Bronchiectasis – A condition that causes irreversible lung damage due to recurrent respiratory infections.
- Autoimmune Disorders – Some individuals with IgG deficiencies develop additional autoimmune conditions over time.
- Organ Damage – Persistent infections can damage vital organs, leading to long-term health issues.
- Sepsis – Severe infections can spread throughout the body, becoming life-threatening.
Proper diagnosis and early treatment reduce the risk of complications and improve overall health outcomes.
Living with Low IgG and Preventing Infections
People with IgG deficiencies can take several steps to reduce the risk of infections and maintain a good quality of life. These include:
- Practicing good hygiene, such as regular handwashing
- Avoiding crowded places during flu season
- Wearing masks when necessary to prevent exposure to airborne germs
- Staying up to date with vaccines, as recommended by a healthcare provider
- Seeking medical attention at the first sign of infection
Regular monitoring and a proactive approach to health can help individuals with low IgG live healthier lives.
Managing Low IgG for a Healthier Life
Knowing how IgG supports your immune system is key to managing its deficiency. If diagnosed with low IgG, regular checkups and proper treatment can help maintain your health.
Taking precautions, staying informed, and following medical advice reduce the risk of infections and complications. With the right approach, individuals with low IgG can protect their well-being and lead a healthier life.