Tests often come back normal despite health problems. For example, hemoglobin levels may be within the normal range although the person is not getting enough oxygen because hg displaces O2.
Many people have subclinical symtoms such as getting up several times a night to urinate due to hg induced kidney damage.
Mercury initially raises WBC but over time WBC levels become depressed.If a person gets pneumonia ,staph or some other serious infection, they are not likely to associate the infection with their hg fillings unless of course they're on this forum.