There are many things that affect thyroid antibody levels and they are called "triggers".
Copy and pasted from the site of thyroid guru, Elaine Moore:
"Known triggers include cigarette smoke, stress, low selenium levels, seasonal and food allergies, sex steroids particularly estrogens, excess dietary iodine, and trauma.
Thyroid cells may also be injured by oxidative stress related to the immune system's response to low antioxidant levels.
Suspected environmental triggers include retroviruses, Yersinia and other enteric bacteria, and aspartame in artificial sweeteners.
The immune mechanisms that contribute to disease from environmental agents include: increased cell destruction or apoptosis, thyroid autoantibody production, inflammation as white blood cells invade thyroid tissue, and the production of cytotoxic (destructive to cells) immune system chemicals known as cytokines."
To read more of the above and get info about
thyroid antibodies, read here:
elaine-moore.com/Articles/Graves%E2%80%99DiseaseArticles/ThyroidDiseaseTriggers/tabid/183/Default.aspx