DefinitionPrimary hyperparathyroidism is an endocrine disorder in which the parathyroid glands in the neck produce too much parathyroid hormone (PTH).See also:HyperparathyroidismSecondary hyperparathyroidismAlternative NamesParathyroid-related hypercalcemia; Hyperparathyroidism - primaryCauses, incidence, and risk factorsThe parathyroid glands are located in the neck, near or attached to the back side of the thyroid gland. They produce parathyroid hormone, which controls calcium, phosphorus, and vitamin D levels within the blood and bone.When calcium levels are too low, the body responds by increasing production of parathyroid hormone. This increase in parathyroid hormone causes more calcium to be taken from the bone and more calcium to be reabsorbed by the intestines and kidney. When the