Something I found on the web that made sense and helped me:
"We recommend that you do not reference any letter to a medical school as a "letter of intent." In general, schools are not weighing their decision on you based on whether you say you will attend that school. A "letter of interest" on the other hand, where you may update a school on your recent activities/accomplishments, emphasizes the strength of your interest, and explains how/why you are particularly well matched to the school, is much more appropriate. There are cases, however, when the term "intent" to attend a school that is your top choice is appropriate to be used."