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Approved by the Cancer.Net Editorial Board, 06/2022

About the parathyroid glands

The parathyroid glands are 4 small glands. They are located near the thyroid gland in the neck or chest, which is also called the upper mediastinum. They are part of the endocrine system. Like all parts of the endocrine system, the parathyroid glands play an important role in regulating hormones in the body. These glands make parathyroid hormone (PTH), which regulates the levels of calcium and phosphorus in the blood.

About parathyroid cancer

Cancer begins when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. A parathyroid tumor usually develops in 1 of the 4 parathyroid glands.

A parathyroid tumor, whether it is benign or malignant, can cause significant problems because this type of tumor causes the amount of calcium in the blood to rise, resulting in a serious condition called hypercalcemia. The doctor may need to quickly treat hypercalcemia if the person is having life-threatening symptoms.

This section covers tumors found in the parathyroid glands. Learn more about tumors that begin in the thyroid gland in a separate guide on this same website.