IgG (Immunoglobulin G)
Here’s what it reflects — and what to do about it.
Longetic pulls together every lab and record you’ve had, follows how IgG (Immunoglobulin G) changes over time, and explains what’s shifting — so you walk into your next appointment prepared, with reminders for retests along the way.
What is IgG (Immunoglobulin G)?
The most abundant circulating antibody, reflecting longer-term immune memory from past infections, vaccines, or immune activity.
IgG makes up the majority of antibodies circulating in the blood and represents long-term immune memory built from past infections and vaccinations. It is the only antibody type that crosses the placenta, providing temporary protection to a newborn. IgG exists as four subclasses, each with a somewhat different role in the immune response. Elevated total IgG can be seen with chronic infections, inflammation, or some autoimmune conditions, while low levels are associated with certain immune deficiencies and recurrent infections. Clinicians typically order total IgG alongside IgA and IgM as part of a broader immune function or recurrent infection workup, interpreting the result together with clinical history.
Lifestyle factors that influence this marker
- Aim for a balanced, nutrient-rich eating pattern that supports overall immune health
- Stay physically active with regular moderate exercise
- Prioritize consistent, restorative sleep
- Practice stress-management techniques
- Avoid smoking
- Moderate alcohol intake
Tests often checked alongside this
- IgA (Immunoglobulin A) — often reviewed together as part of a full immunoglobulin panel
- IgM (Immunoglobulin M) — often reviewed together as part of a full immunoglobulin panel
- IgG Subclass 1 through 4 — may be checked individually if total IgG is abnormal
How this can show up in how you look and feel
- May be associated with recurrent infections if persistently low
- May be associated with fatigue
- May be associated with symptoms related to an underlying chronic condition if elevated
What can affect this marker
- Age
- Pregnancy
- Medications
- Infection
- Lab variability between testing methods
What to track over time
- Whether levels remain stable if monitoring a known immune condition
- How this result correlates with infection history over time
- Whether subclass testing is considered if total IgG is abnormal
What to ask your doctor
- Does this result suggest I should have IgG subclasses checked individually?
- How does this relate to my IgA and IgM levels?
- Could this be related to my infection history?
- Is any follow-up testing recommended?
This glossary entry is for informational purposes only and is not a substitute for professional medical advice. Read our Terms of Use.
References
About our sources
Official sources
Government health agencies, national institutes, and intergovernmental bodies whose guidelines carry regulatory or policy weight.
Clinical / professional
Medical societies, specialty colleges, and professional associations whose consensus statements reflect clinical practice standards.
Peer-reviewed research
Original research articles and systematic reviews published in indexed journals and verified through PubMed or DOI.