In postoperative hypoparathyroidism, the injured parathyroid glands are unable to increase the secretion of PTH and, thus, predispose VDD patients to more severe hypocalcemia because their calcium regulation is more dependent on serum PTH levels than that of patients without vitamin D insufficiency [13, 15, 16, 28]. The gene discussed is PTH; the disease is hypoparathyroidism.