Causes of high parathyroid hormone include parathyroid adenoma, hyperplasia, adenocarcinoma, etc. Its harms include hypercalcemia, bone pain, fibrocystic osteitis, osteoporosis, bone fracture and other problems in the skeletal system, and harms in the urinary system include renal stone, chronic pyelonephritis, renal insufficiency and so on. 1. Causes: most of the parathyroid adenomas are single adenomas, which are usually small in size and have complete envelope; parathyroid hyperplasia is commonly caused by hypocalcemia caused by chronic renal insufficiency, which stimulates parathyroid cell hyperplasia; parathyroid adenocarcinoma patients are typically characterized by severe hypercalcemia as well as easy to recur after treatment. Others are renal insufficiency and osteochondrosis. 2. Harm: Hypercalcemia can lead to central nervous system abnormality, memory loss, emotional instability, etc. Damage to neuromuscular system can lead to lethargy, muscle weakness, and myasthenia in the long run, and patients with severe hypercalcemia can be threatened to life. It can also cause problems in the skeletal system and urinary system. If you have increased parathyroid hormone, it is recommended that you consult a doctor in a timely manner to identify the cause and standardize treatment.