What is hyperparathyroidism?
Hyperparathyroidism is excessive production of parathyroid hormone by the parathyroid glands. Hyperparathyroidism is caused by overactive parathyroid glands. Overactive parathyroid glands produce high levels of parathyroid hormones, which, in turn, results in increased levels of calcium in the blood stream. The excess calcium released by the bones leads to
osteoporosis and osteomalacia (both bone-weakening diseases). Another result of hyperparathyroidism is kidney stones, because of high levels of calcium excreted into the urine by the kidneys.
Thyroid glands and parathyroid glands, despite their similar name and proximity, are entirely separate, and each produces hormones with different functions. Hyperparathyroidism may be primary or secondary. It most often occurs in those over age 30, and most commonly in patients 50 to 60 years old. It rarely occurs in children or the elderly. Women are affected by the disease up to three times more often than men. It is estimated that 28 of every 100,000 people in the United States will develop hyperparathyroidism each year.
Normally, parathyroid glands produce the parathormone as calcium levels drop and lower to meet the demands of a growing skeleton, pregnancy, or lactation. However, when one or more parathyroid glands malfunctions, it can lead to overproduction of the hormone and elevated calcium level in the blood. Therefore, a common result of hyperparathyroidism is hypercalcemia, or an abnormally high level of calcium in the blood. Primary hyperparathyroidism occurs as a malfunction of one of the glands, usually as a result of a benign tumor, called adenoma. Secondary hyperparathyroidism occurs as the result of a metabolic abnormality outside the parathyroid glands, which causes a resistance to the function of the parathyroid hormones. Primary hyperparathyroidism is one of the most common endocrine disorders, led only by diabetes and hyperthyroidism.
The parathyroid glands are located at the front and base of the neck around the thyroid gland. They produce parathyroid hormone, which regulates calcium, phosphorus, and magnesium 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 cacium level returns to normal, parathyroid hormone production slows down.
Excess parathyroid hormone can be produced for a variety of reasons. In some cases, parathyroid hormone is produced without regard to the calcium levels. This is called "primary hyperparathyroidism" and is caused by enlargement of one or more of the parathyroid glands. It is a common disorder affecting about 1 in 1000 people. The high levels of calcium and parathyroid hormone affect several body systems, including the skeletal, gastrointestinal, renal, muscular, and central nervous system. "Secondary hyperparathyroidism" is when the body produces extra parathyroid hormone because the calcium levels are too low. This is seen when vitamin D levels are low or when calcium is not absorbed from the intestines. Correcting the calcium level and the underlying problem will bring the parathyroid levels in the normal range. If the parathyroid glands continue to produce too much parathyroid hormone even though the calcium level is back to normal, this is called "tertiary hyperthyroidism" and occurs especially in patients with kidney problems.