Answer :
Answer: The parathyroid hormone is the major controller for blood calcium levels. Although calcitonin secretion is a counter mechanism to parathyroid hormone, it does not play a major role in calcium balance. Catecholamine and thyroid hormone levels do not affect serum calcium level.
Explanation: Low serum calcium levels stimulate the parathyroid glands to release parathyroid hormone (PTH). PTH is the primary controller for blood calcium levels. When calcium levels drop, the parathyroid glands increase PTH secretion, which raises blood calcium levels. PTH helps maintain the right balance of calcium in the body by:
Telling bones to release calcium into the blood
Helping the intestines absorb calcium from food
Helping the kidneys keep calcium in the blood instead of getting rid of it through urine
