Inclusion Criteria:  Patients aged 19 to 70 years old Patients undergoing total thyroidectomy due to thyroid disease Patients who consented to the study and obtained consent for the study  Exclusion Criteria:  Patients with confirmed hypocalcemia or hypercalcemia before surgery Patients receiving calcium or vitamin D treatment before surgery, patients with excessive vitamin D Patients with a previous history of parathyroid disease or a history of cervical irradiation Patients with confirmed parathyroid comorbidity Patients with diseases or conditions that cause hypercalcemia or hypercalciuria (myeloma, bone metastases, or other malignant bone diseases) Patients with confirmed renal dysfunction (glomerular filtration rate <60mL/min/1.73m2) before surgery or with a history of chronic renal failure Renal stone disease patient, kidney stone disease patient Patients with bowel disease that may affect serum vitamin D levels (celiac disease, small intestine resorption disease, small bowel resection history) Patients taking drugs that may affect serum calcium or vitamin D levels (anticonvulsants, bisphosphonates, cisplatin, aminoglycosides, diuretics, proton pump inhibitors, glucocorticoid benzodiazepine derivatives, etc.) Uncontrolled hypertension, diabetes, and clotting disorders Cardiovascular disease (angina pectoris, heart failure, myocardial infarction, coronary artery disease, history of arrhythmia treatment, stroke, transient ischemic attack), and taking medications for arrhythmia Drug Abuse and Alcohol Abuse Patients who participated in other drug clinical trials within 30 days Patients with a history of allergies to drugs For women, pregnant and lactating patients Patients judged unsuitable by the person in charge of the clinical trial Patients with genetic problems such as galactose intolerance, lactose deficiency, or glucose-galactose malabsorption disorder