Hyperparathyroidism means that the parathyroid glands are producing an excess of a hormone called parathyroid hormone, which in turn causes elevations in the levels of calcium circulating in the bloodstream.
Primary hyperparathyroidism has become a relatively common condition, especially among the elderly. The incidence of this disease is approximately 25-28 cases/100,000 people per year. Among white women older than 60 the incidence actually approaches 190 cases/100,000 women/year.
Although most people are born with 4 parathyroid glands, a very small percentage of people are born with 3 or 5 of these little glands. And a normal gland is very little indeed, about the size of a baby pea. Furthermore, the parathyroid glands can migrate to some unusual positions in the neck, and can rarely be found in the chest. In most situations, the parathyroid glands are normally intimately associated and attached to the adjacent thyroid gland. Luckily, the vast majority of people who have hyperparathyroidism have only one of these glands enlarge to cause the problem.