Why does the level of calcium decreases after undergoing thyroidectomy?

Question

Why does the level of calcium decreases after undergoing thyroidectomy?

Answer 1

Hypocalcemia may be associated with low PTH levels caused by resection of the parathyroid glands.

As you may know, Parathyroid hormone (PHT) secreted by the parathyroid gland and calcitonin secreted by the thyroid gland maintain serum calcium levels at a range of between 8.5 to 10.5. The parathormone can also affect renal functions to retain more calcium.  When blood calcium rises from too much para-thyroid activity, calcitonin reduces availability of calcium from bone.

Answer 2

the thyroid produces hormones that help regulate the levels of calcium

Answer 3

Well calcium shouldn't really decrease after thyroidectomy. The thyroid gland doesn't have anything to do with controlling the calcium level in the blood. However, sitting on the thyroid gland are 4 tiny glands called the parathyroid glands. These ARE important for controlling calcium - they secrete a hormone called PTH (parathyroid hormone). Too little PTH means the level of calcium in the blood drops. Ideally, when a thyroidectomy is done, the parathyroids are left in place. But because they are small it can be hard to separate them so sometimes they get removed along with the thyroid - this may be accidental or just unavoidable. So if they get removed, there is not enough PTH and so calcium decreases.

Mostly, this doesn't happen, but it's just one those things that has to be monitored after a thyroidectomy just in case.