PTH, also known as parathyroid hormone, is a hormone secreted by the parathyroid glands that regulates blood calcium and phosphorus metabolism. Excessive parathyroid hormone is mainly seen in patients with parathyroid adenoma or parathyroid hyperplasia. The main hazards of high parathyroid hormone are as follows: First, hypercalcemia. PTH can promote calcium absorption and mobilization of bone calcium into the blood, leading to further increase in blood calcium. Second, excessive PTH tends to increase osteoclast activity and osteolytic destruction, leading to fibrocystic osteitis and pathological fractures. Third, long-term PTH and excessive blood calcium are prone to multiple urinary stones, which can affect kidney function and even lead to renal insufficiency. Fourth, long-term hypercalcemia can cause mental and neurological changes, leading to emotional instability, personality changes and even psychotic episodes. V. Severe hypercalcemia can cause hypercalcemic crisis and endanger patients’ lives.