Serum calcium is blood calcium, normal human blood calcium concentration is 2.15-2.60mmol/L, if the concentration exceeds 2.60mmol/L, it is hypercalcemia. Clinically, there are many reasons for the increase of serum calcium, and the common reasons are: First, primary hyperparathyroidism, which can be seen in adenoma and adenocarcinoma of parathyroid glands, etc. The parathyroid glands can secrete parathyroid hormone, and the parathyroid hormone can effectively elevate the concentration of calcium in the blood, so the hyperparathyroidism will cause the abnormality of increase in the concentration of calcium in the blood. Second, some malignant diseases, the most common are multiple myeloma, osteosarcoma and so on. Especially for multiple myeloma, because myeloma cells can activate human osteoclasts, inhibit human osteoblasts, and dissolve bones, which leads to the release of calcium ions into the serum, and the situation of high serum calcium occurs.