<prompt> Answer this question truthfullyWhat classification does hypercalcemia belong to?  <response>: <reason> Common Terminology Criteria for Adverse Events CTCAE grade classifies hypercalcemia into 4 grades on the basis of corrected serum calcium CSC: Grade Corrected serum calcium CSC Grade 1 Corrected serum calcium of ULN - 11.5 mgdL; ULN - 2.9 mmolL; Ionized calcium ULN - 1.5 mmolL Grade 2 Corrected serum calcium of 11.5 - 12.5 mgdL; 2.9 - 3.1 mmolL; Ionized calcium 1.5 - 1.6 mmolL; symptomatic Grade 3 Corrected serum calcium of 12.5 - 13.5 mgdL; 3.1 - 3.4 mmolL; Ionized calcium 1.6 - 1.8 mmolL; hospitalization indicated Grade 4 Corrected serum calcium of 13.5 mgdL; 3.4 mmolL; Ionized calcium 1.8 mmolL; life-threatening consequences ULN Upper limit of normal 10.8 mgdL Corrected calcium may lead to confusion that the result is due to error and shall be corrected. So, the term adjusted calcium is preferred over corrected calcium. Adjusted total calciummgdL Total calciummgdL 0.8 4AlbumingdL or Adjusted total calciummmolL Total calcium mmolL 0.02 40AlbumingL Hypercalcemia may be classified according to severity into 3 groups: Severity Calcium concentration Key Points Mild hypercalcemia 3.0 mmolL Often asymptomatic No urgent correction needed Moderate hypercalcemia 3.03.5 mmolL Tolerated well if there is a slow rise Symptoms may be present Treatment indicated in symptomatic cases Severe hypercalcemia 3.5 mmolL Urgent correction is recommended Risk of dysrhythmia and coma if not correctedHypercalcemia associated with malignancy may be classified according to mechanism of increased production of calcium into four types: Disorder Mechanism of hypercalcemia Clinical features Laboratory findings PTH Calcium Phosphate Other findings Humoral hypercalcemia of malignancy Tumor cells secretes parathyroid hormone-related protein PTHrP which has similar action as parathyroid hormone. Most common cause of malignancy related hypercalcemia Usually present with solid tumors -- Normal PTHrP Normal calcitriol Osteolytic tumors Multiple myeloma produces osteolysis of bones causing hypercalcemia. Osteolytic metasteses can cause bone resorption causing hypercalcemia. Commonly present in multiple myeloma and breast cancer -- -- Production of calcitirol Some tumors has ectopic activity of 1-alpha-hydroxylase leading to increased production of calcitriol. Calcitriol is active form of vitamin D and causes hypercalcemia. Commonly present in lymphomas and in some ovarian germ cell tumors -- -- Calcitriol Ectopic parathyroid hormone Some tumors leads to ectopic production of parathyroid hormone. In rare instances, small cell carcinoma of lung may produce hypercalcemia by this process Normal Normal calcitriol 