Hypo is short for “hypothyroid” . In this condition, there is not enough thyroid hormone being naturally produced to sustain cell metabolism in the body. All the systems slow down (much the way they revved up when we had too much thyroid hormone.)
RAI does not necessarily “kill” the entire thyroid, nor is it necessarily intended to do so. Some RAI treatments are designed to leave some thyroid tissue still functioning. Some treatments are designed to get rid of more than a majority of the gland, even all of it. But the dose of RAI given is a bit of a guess (based on the size of our thyroid and the level of hyperactivity), and sometimes, albeit rarely, an initial treatment does not get rid of enough of the thyroid to eliminate, permanently, hyperthyroidism.
How long it takes for thyroid cells to die out after RAI varies with the amount of RAI given, and our own body’s reaction to it. A rule of thumb that I’ve read is three to six months. The effects can usually be seen before then, but the complete results take longer. I was technically hypothyroid four weeks after my RAI treatment.
Bobbi
