The parathyroid glands are small glands located near the thyroid gland. A normal parathyroid might be as small as a grain of rice. Occasionally, a person is born with one or more of the parathyroid glands embedded in the thyroid, in the thymus, or located elsewhere in the neck or chest.
The parathyroid glands secrete PTH, a hormone that helps maintain the correct balance of calcium in the body. PTH regulates the level of calcium in the blood, release of calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine.
If the parathyroid glands secrete too much hormone, blood calcium rises. This condition of excessive calcium in the blood, called hypercalcemia, is what usually signals the doctor that something may be wrong with the parathyroid glands. In 85 percent of people with primary hyperparathyroidism, a benign tumor called an adenoma has formed on a single parathyroid gland, causing it to become overactive. Less frequently, an excess of PTH hormone comes from two or more enlarged parathyroid glands, a condition called hyperplasia. Very rarely, hyperparathyroidism is caused by cancer of a parathyroid gland.
This excess PTH triggers the release of too much calcium into the bloodstream. The bones may lose calcium, and too much calcium may be absorbed from food. The levels of calcium may increase in the urine, causing kidney stones.
Conventional open (4-gland) parathyroid exploration was considered the standard of care for treatment of primary hyperparathyroidism until the 1990s, when improvements in imaging techniques made limited exploration feasible. Now, many surgeons have adopted limited parathyroid exploration as their preferred surgical approach. Approximately 90% of individuals with primary hyperparathyroidism have only one diseased gland. Through the use of preoperative imaging techniques including parathyroid sestamibi (a nuclear medicine test) and ultrasound, an abnormal parathyroid gland can often be identified. In such cases, a much smaller incision can be utilized and the surgery and recovery time are typically much shorter.