Parathyroid tumors occur in the parathyroid glands, four small glands located behind the thyroid. Although the majority of parathyroid tumors are benign, carcinomas of the parathyroid (parathyroid cancer) do develop, and it is important to be able to properly diagnose and treat them.
The parathyroid glands secrete a hormone called parathyroid hormone (also known as PTH or parathormone), which regulates the body’s calcium levels. PTH acts on special PTH receptors in three key areas of the body: the bones, kidneys and intestines. PTH mobilizes the bones to release stored calcium, increases calcium reabsorption from the kidneys, and increases calcium absorption in the intestines via activation of vitamin D. The more PTH secreted, the higher the resulting level of blood calcium. Like many systems in the body, the parathyroids respond to feedback inhibition, so that if blood calcium is very high, this signals the parathyroid glands to reduce PTH production.
When parathyroid tumors develop, they cause heightened production of PTH, which in turn results in elevated blood calcium levels (a condition known as hypercalcemia). The tumor may affect a single gland, or tumors may occur simultaneously in multiple glands. This is more common in certain genetic diseases. Parathyroid cancer is generally slow-growing and rarely metastases. However, the hyperparathyroidism (excess production of PTH) caused by the parathyroid tumors can be quite dangerous. Additionally, parathyroid tumors have a reasonably high degree of recurrence. Therefore, adept surgical management and supportive care to manage percalcemia is important in effective treatment of parathyroid cancer.