The parathyroid gland consists of 4 small glands that are located next to, behind or under the thyroid gland. The most important function of the parathyroid gland is the production of parathyroid hormone and thus the control of calcium levels. The most common cause of increased calcium levels in the blood is primary hyperparathyroidism due to an overactive parathyroid adenoma with increased parathyroid hormone secretion. If left untreated, this disease can lead to secondary complications such as osteoporosis, kidney stones, gallstones or depression. In addition to the diagnosis and treatment of primary hyperparathyroidism, my area of work also includes the treatment of parathyroid hypofunction (hypoparathyroidism), for example after surgical interventions.