Hyperparathyroidism is a condition caused by excessive levels of parathyroid hormone in the body. Usually this is caused by benign tumors of the parathyroid glands, although occasionally the disease occurs secondary to renal failure or other systemic illnesses. Mild hyperthyroidism is managed with medication, but severe primary hyperparathyroidism may require surgical removal of the parathyroid glands. In some cancer patients, malignant tumors release a parathyroid-like hormone with hypercalcemia, which mimics hyperparathyroidism. You could research further on medical search engines such as 'webmd'.
