Conditions and tumours of the parathyroid glands

Most of the time, a problem with a parathyroid gland is not caused by cancer. The cause is much more likely to be a non-cancerous tumour called a parathyroid adenoma. Or the cause could be hyperplasia, which is a non-cancerous condition. Parathyroid cancer (also called parathyroid carcinoma) is extremely rare.

Most people with parathyroid tumours have hyperparathyroidism. This means that one or more of the parathyroid glands make too much parathyroid hormone (PTH). The glands are often described as being overactive. When hyperparathyroidism is caused by a parathyroid gland or glands making too much PTH, it's called primary hyperparathyroidism. Sometimes hyperparathyroidism is caused by something outside the parathyroid glands, such as kidney disease or vitamin D deficiency. This is called secondary hyperparathyroidism.

Primary hyperparathyroidism causes too much calcium in the blood (called hypercalcemia). In some cases, hypercalcemia can cause serious problems. Find out more about hypercalcemia.

A non-cancerous (benign) condition of the parathyroid glands is a change to parathyroid gland cells, but it is not cancer. Non-cancerous conditions do not spread (metastasize) to other parts of the body and are not usually life-threatening.

Parathyroid hyperplasia is the most common non-cancerous condition of the parathyroid glands. It is an enlargement of all 4 parathyroid glands caused by an overgrowth of cells (called hyperplasia). This condition can cause hyperparathyroidism. It is most often seen in people who have kidney failure.

The treatment for parathyroid hyperplasia is usually surgery to remove most of the glands. Three of the 4 parathyroid glands are removed entirely. Sometimes, half of the fourth gland is removed but half is left so that your body can still make PTH and maintain blood calcium levels.

Other non-cancerous conditions of the parathyroid include:

• hypoparathyroidism (low levels of PTH)
• parathyromatosis (pieces of parathyroid tissue scattered throughout the tissues of the neck and middle of the chest)

A non-cancerous tumour of the parathyroid glands is a growth that does not spread to other parts of the body. Non-cancerous tumours are not usually life-threatening. They are typically removed with surgery and do not usually come back (recur).

Parathyroid adenoma is the most common non-cancerous tumour of the parathyroid glands. Often, it is found in only one parathyroid gland. But sometimes it can occur in more than one parathyroid gland. This is called multiglandular parathyroid disease. Multiglandular parathyroid disease can sometimes be caused by hereditary conditions like multiple endocrine neoplasia (MEN).

Parathyroid adenoma is the most common cause of primary hyperparathyroidism. About 80% of primary hyperparathyroidism is caused by a single parathyroid adenoma.

Surgery is often done to completely remove the tumour and the affected parathyroid glands (called a parathyroidectomy).

A cancerous tumour of the parathyroid glands can grow into nearby tissue and destroy it. The tumour can also spread to other parts of the body. Cancerous tumours are also called malignant tumours.

Parathyroid cancer is a cancerous tumour of the parathyroid glands. It is also called parathyroid carcinoma. Parathyroid cancer is very rare.

Most people with parathyroid cancer have hyperparathyroidism. But less than 1% of people with primary hyperparathyroidism have parathyroid cancer.

Parathyroid cancer can grow into nearby areas such as the thyroid and soft tissue. It usually grows slowly. Doctors often describe these slow-growing cancers as indolent. A cancerous tumour in the parathyroid is often larger than a parathyroid adenoma.

It is often hard to tell the difference between parathyroid cancer and a parathyroid adenoma based on imaging and other tests. Parathyroid cancer can cause the same symptoms as a parathyroid adenoma. Surgery is needed to make a definite diagnosis of parathyroid cancer.