I agree that a little more information is needed. For someone on full replacement meds, a week can make a BIG difference. I would never do that myself.
Now if it is under medical direction, that is different.
a week may not be something to worry much - at the time you aren't taking it... but after you resume - it could take a huge length of time to get your body balanced again since these are hormone drugs and are not quick fixes.
There's little information here on what meds you speak of - and your condition to really say what problems could be.
Can I ask why you're contemplating doing that?
Probably not much. I went off mine for 6 weeks prior to radioactive iodine and I still felt okay after one week. As long as you start again after the week.