Immunoglobulin G (IgG)

What it is

Immunoglobulin G, or IgG, is a type of protein that plays a crucial role in your immune system. Think of it as one of the body's main defenders against infections. It's the most common type of antibody found in your blood and other body fluids. Antibodies are Y-shaped proteins produced by a type of white blood cell called B cells. Their job is to identify and neutralise foreign invaders like bacteria and viruses. IgG is particularly important because it's the main antibody involved in your body's long-term memory of infections. This means if you encounter the same germ again, your body can mount a quicker and stronger defence.

Why it matters

The level of IgG in your blood can give doctors valuable clues about how well your immune system is working. A normal level of IgG suggests your body is likely producing enough antibodies to fight off infections effectively. If your IgG levels are too high or too low, it might indicate an underlying issue that needs further investigation. For example, consistently low IgG levels could mean your immune system is struggling to defend itself, potentially leading to more frequent or severe infections. Conversely, very high levels might suggest your body is overreacting to something, perhaps an ongoing infection or an autoimmune condition where the immune system mistakenly attacks the body's own tissues.

What can cause it to be high or low

High IgG levels can be associated with a number of conditions. These might include chronic infections, such as certain viral infections like cytomegalovirus (CMV) or Epstein-Barr virus (EBV), or bacterial infections that persist over time. Autoimmune diseases are another common reason for elevated IgG; conditions like rheumatoid arthritis or lupus can trigger the immune system to produce more antibodies. Certain types of cancer, particularly those affecting the blood cells like multiple myeloma, can also lead to significantly high IgG levels. In some cases, high IgG can be a sign of a condition called chronic graft-versus-host disease, which can occur after a stem cell transplant.

Low IgG levels, also known as hypogammaglobulinemia, can make you more susceptible to infections. This can be caused by a variety of factors. Some people are born with a genetic predisposition to produce lower levels of antibodies, known as primary immunodeficiency disorders. More commonly, low IgG can be acquired later in life. This can be associated with certain medications, such as chemotherapy drugs or immunosuppressants used to treat autoimmune diseases or prevent organ transplant rejection. Chronic illnesses, liver disease, kidney disease, and malnutrition can also impact IgG production. In some instances, certain cancers or treatments for cancer can also lead to reduced IgG levels.

Lifestyle factors that may help

While your IgG levels are primarily determined by your immune system's function and any underlying medical conditions, certain lifestyle choices can support overall immune health. A balanced diet rich in vitamins and minerals is important for the proper functioning of all immune cells, including those that produce antibodies. Regular, moderate exercise has also been linked to a healthier immune response. Getting enough quality sleep is crucial, as sleep deprivation can negatively affect immune function. Managing stress effectively through techniques like mindfulness or yoga may also be beneficial for your immune system. Avoiding smoking and limiting alcohol intake are generally recommended for good health, including supporting your immune defences.

Questions to discuss with your GP

If your IgG levels have been measured, you might find it helpful to discuss the results with your GP. Here are some questions you could consider asking:

• What does my specific IgG level mean in the context of my overall health?
• Are my IgG levels considered high, low, or within the normal range for me?
• Could my current medications or any past medical conditions be affecting my IgG levels?
• What are the potential implications of my IgG level for my risk of infection?
• Are there any further tests you would recommend to understand these results better?
• What steps, if any, can I take to support my immune system's health?