How Does MEN1 Affect the Endocrine Glands?
The Parathyroid Glands The parathyroids are the endocrine glands earliest and most often affected by MEN1. The human body normally has four parathyroid glands, which are located close to the thyroid gland in the front of the neck. The parathyroids release into the bloodstream a chemical called parathyroid hormone, which helps maintain a normal supply of calcium in the blood, bones, and urine. In MEN1, all four parathyroid glands tend to be overactive. They release too much parathyroid hormone, leading to excess calcium in the blood. High blood calcium, known as hypercalcemia, can exist for many years before it is found by accident or by family screening. Unrecognized hypercalcemia can cause excess calcium to spill into the urine, leading to kidney stones or kidney damage. Nearly everyone who inherits a susceptibility to MEN1 (a “carrier”) will develop overactive parathyroid glands (hyperparathyroidism) by age 50, but the disorder can often be detected before age 20. Hyperparathyroidism
