What does a low IgG result mean?

A low IgG result from a consumer blood test indicates a reduced level of immunoglobulin G, the most abundant antibody in the bloodstream. IgG is crucial for long-term immunity against bacteria and viruses. Low IgG can be associated with primary immunodeficiency disorders (e.g., common variable immunodeficiency), secondary causes such as certain medications (corticosteroids, immunosuppressants), protein-losing conditions (nephrotic syndrome, enteropathy), or even physiological variation. However, a single low IgG value is not diagnostic. It must be interpreted alongside total immunoglobulins (IgA, IgM, IgE), clinical history, and vaccination responses. MyBody-X tests are screening tools, not diagnostic devices. A low IgG result warrants medical follow-up; do not self-treat. Evidence level: unclear, as the provided context does not contain specific IgG-related studies. Caveat: consumer lab tests may have higher variability; confirm with a clinical laboratory.