I was told that your thyroid could quit working as late as four years after radiation so I guess it can occur almost anytime. The trick is to know what normal is. If yours is still working now and you don't know what your levels are, I would recommend getting your TSh, T3 and T4 levels the next time your doctor does a blood test for anything. Then you at least have an idea of what they should be.

As to dosage levels, it is tricky to get to the correct level and usually takes several adjustments. I like Mark, am between dosage levels. I solve this problem by alternating between two dosages. I take synthroid 88 one day, synthroid 100 the next. Mark you might try that rather than skipping doses.

You also have to continue to be tested at least every 6 months because your dosage level may need to be changed. Mine is usually done every 3 or 4 months. After years of being at 2.5 on my alternating doses, I'm suddenly down to .85 or below two tests in a row so an now cutting back on the number of doses of 100. It's a crazy game and you will have to monitor it yourself cuz your doctor will say everything is A-OK as long as it is within that broad range and for you, it may not be. So get the numbers from him and track it yourself.

Take care,
Eileen