If you are worried about your immune system, probably the first thing to look at are the three primary immunoglobulin (IgM, IgA, IgG) levels. I (74-year-old male, high-risk MGUS/SMM) have slightly below normal IgM, and low normal IgA and IgG. Does this make me immunocompromised? Perhaps slightly. Treatments exist - generally replacement therapy - for serious cases.