An over production of parathyroid hormone resulting in high calcium levels in the blood. There are four parathyroid glands located in the neck next to the thyroid gland. There are two types of hyperparathyroidism, primary and secondary. In primary one of the glands produces too much parathyroid hormone usually from a non-cancerous growth of the gland called an adenoma or from a cancer of the gland. Secondary occurs when another disease process causes low levels of calcium resulting in elevated levels of parathyroid hormone. The most common causes of secondary disease is failure of the intestines to absorb calcium, vitamin D deficiency or kidney failure. The elevated calcium levels can result in osteoporosis, kidney stones, hypertension, pancreatitis, peptic ulcers, and heart disease.