Primary Hyperparathyroidism
When an abnormal parathyroid gland ‘goes rogue’ and stops responding to normal signals from the body, it tells the body (unnecessarily) that it needs more calcium. Calcium is then leached from the bones (a cause of osteoporosis) and intestines, and can be deposited in the kidneys (leading to kidney stones) or other areas of the body. A build-up of too much calcium in the bloodstream can be either asymptomatic or can lead to a variety of symptoms.
Some patients with a parathyroid tumor have normocalcemic hyperparathyroidism where the calcium level is normal but the PTH is high. Other patients may have high calcium but high-normal or normal PTH levels. Assuming that there are no other causes of high calcium or high PTH, these patients ALL have primary hyperparathyroidism that should generally be treated.
The cause of overactive parathyroids in 1% of patients is inheritance of a gene abnormality from one parent. The cause of a parathyroid tumor in the other 99% of patients is usually unknown, although radiation therapy to the face or neck can be a factor in causing a single parathyroid tumor.