Hyperparathyroidism is caused by overactive parathyroid glands.
Overactive parathyroid glands produce too much parathyroid hormones, which in turn stimulate increased levels of calcium in the blood stream. Other results of hyperparathyroidism are kidney stones, because of high levels of calcium excreted into the urine by the kidneys. Causes of hyperparathyroidism include benign tumors on the parathyroid glands or enlargement of the parathyroid glands. The following are the most common symptoms of hyperparathyroidism. However, each individual may experience symptoms differently.