OK, here goes. There are two quite separate hormone-producing glands: the thyroid & the parathyroid, either of which can cause problems if they go wrong.
Hyper means excessive activity & hypo means under-activity. Hyper can be caused by a tumour on the gland or by kidney problems. Hypo, which Bing has, is caused by autoimmune deficiency where the body effectively fights itself. In the latter case the seizures are caused by a calcium deficiency which results.
His calcium tablets, which he has been having for months, contain vitD but not enough for him to absorb the calcium fully so he, from Monday, now has a stronger vitD supplement. To complicate things he has been on a steroid to stimulate his appetite, the loss of which is linked to the condition. These tend to supress the ability to absorb calcium!
Anyway we are progressing slowly with his calcium levels needing to checked every two weeks for now.
Mike