Hyperparathyroidism. PTH is not under the control of the hypothalamic-pituitary system. Unknown causes. Some forms can be genetic in origin, but 80% of surgically proven cases are from a single PT adenoma. Hyperplasia of the PT makes up the rest of the cases. In Hyperparathyroidism, bone resorption and formation rates increase. Manifestations can include bone demineralization, kidney stones, serum hypercalcemia. Cardiac problems like bradycardia, heart block, and cardiac arrest.