I was hyper then hypo after RAI and was found to be deficient in Vitamin D.
I've read that "normal" is 30-60, but like Flys4Food said - "optimal" is around 80. And yes, it's common for people with thyroid issues to be deficient. I'm hypO also....
I've read that the optimum level of vitamin D is around 80. I've gotten mine up to 45 (from 21.) I'm hypo.
vitamin D deficiency is common in people with thyroid disorders !!
I am not sure regarding the normal range !