Nancy's diet is deficient in iodine. this will affect the secretion of which hormone?

The secretion of thyroid hormones will be affected if Nancy's diet is deficient in iodine. Particularly the thyroxine and triiodothyronine hormones of the thyroid gland will be affected. These hormones contain traces of iodine and a deficiency of this will result to diseases like, goiter and cretinism (a delay in the developmental growth). 

Iodine deficiency is common in places where there is little or no supply of iodine-rich food (e.g. seafood, fish). It is also common in mountainous places or regions where food is grown in soil that is poor in iodine.