they have nothing to do with eachother, ironically. barb135 is exactlly right.
If I remember correctly, the parathyroids control calcium in your body. Though they are located directly behind the thyroid, the only thing they share is the names. They do not share functions. Sally is right though - parathyroids can be damaged from thyroid surgery, radiation, etc.
You can get tons of information regarding parathyroids @ www.parathyroid.com
Hi,
I beleive that they are not related. The thyroid and parathyroid are distinct organs, with distinct functions, though they are very close to eachother.
However, they can be affected if the thyroid is surgically removed, or from radiation, i'd guess. But this would be hypo, not hyper.
I understand that hyperparathyroid is usually caused by one of the 4 hyperparathyroid glands going 'bad'. Treatment for this would be to surgically remove the affected gland.