Hypercalcemia is one of the more common metabolic disorders in the endocrine clinic. In mild cases, it is asymptomatic and only detected during routine screening, while in severe cases it can be life-threatening. The most common clinical causes of hypercalcemia are primary hyperparathyroidism and malignancy, which account for more than 90% of the causes of the cure. Although the prevalence of hypercalcemia is not high, there are many causes of hypercalcemia, and the causes of hypercalcemia are briefly described next. I. Primary hyperparathyroidism II. Malignant tumors Many types of tumors have been reported at home and abroad to cause hypercalcemia. Certain tumors are common types that cause hypercalcemia, such as lung cancer, breast cancer, renal cell tumor, ovarian cancer, multiple myeloma, etc. Foreign reports say that the incidence of hypercalcemia in lung cancer and breast cancer is about 24%-28%; while certain tumor types such as intestinal adenocarcinoma, gastric adenocarcinoma, thyroid cancer, and central nervous system malignancies rarely have hypercalcemia. The prognosis of cancer patients with hypercalcemia is extremely poor. Some observations indicate that the survival rate is only 50% within 30 days after the appearance of hypercalcemia, and some reports suggest that the average survival rate is 4-6 weeks. Endocrine diseases 1. thyrotoxicosis; 2. pheochromocytoma; 3. hyperalgesia; 4. vasoactive intestinal peptide secreting tumor (VIP tumor); 5. others: acromegaly, growth hormone therapy. IV. Nodular and other sarcoidosis V. Drug-induced hypercalcemia 1. vitamin D toxicity; 2. vitamin A toxicity; 3. thiazide diuretics; 4. lithium salt therapy; 5. other drugs Estrogens and aminophylline have been reported to cause hypercalcemia, the pathogenesis of which is unclear. VI. Other causes of hypercalcemia 1. Braking weightlessness (astronauts), prolonged bed rest, especially Paget’s disease and other patients with high bone conversion rate can develop hypercalcemia with prolonged bed rest. Braking for several days to weeks may increase osteoclastic bone resorption and decrease osteoblastic bone formation, which may cause kidney stones and osteochondrosis at the same time. 2. Familial hyponatremia hypercalcemia. 3, lactobacillus syndrome. Hypercalcemia, hyperphosphatemia, metabolic alkalosis and renal insufficiency due to excessive intake of calcium (2-8g of elemental calcium per day) and absorbable antacids. 4. Idiopathic hypercalcemia in infancy. The above is a brief summary of the causes of hypercalcemia, please correct me if there are any deficiencies.