1) Primary hyperparathyroidism. It is the most common cause of hypercalcemia, commonly found in parathyroid adenoma and parathyroid hyperplasia, parathyroid cancer a few. Many because of abnormal secretion of PTH to increase calcium.
2) Malignant tumors. Hypercalcemia that caused by malignant tumors is secondly common. In malignant tumor, about 70% of cause is bone metastatic tumor, 20% of leukemia, non-metastatic tumors only 10%. Bone metastases caused by increased calcium, on the one hand, because of bone damage, the release of osteocalcin; on the other hand, bone metastases can also produce some cytokines, such as transforming growth factor, epidermal growth factor, tumor necrosis factor, which factor in the Local can be shown to promote bone absorption, the activity of osteocalcin release. No systemic metastatic tumor osteoclastic Osteolysis is generated because of PTH or PTH-like substances, prostaglandins, osteoclast activating factor, such as the relevant factor.
3) Secondary hyperparathyroidism. Chronic nephritis, a lack of vitamin D, low-phosphorus repeated hemodialysis and kidney failure caused a long-term hypocalcemia can stimulate parathyroid hyperplasia, PTH secretion, resulting in hypercalcemia.
4) Hyperthyroidism. Thyroid hormone and iodine Histidine three (T3) can promote bone absorption, so that elevated serum calcium, urinary calcium also increased. There is 15% -20% of patients with moderate hyperthyroidism with hypercalcemia.
5) Toxicosis with vitamin D. Long-term taking vitamin D, lead to increased blood calcium, the formation of long-standing kidney stones and nephrocalcinosis advanced uremia cause. Because of elevated blood calcium, can suppress PTH secretion by serum PTH reduced.