Enlarged and hypercellular parathyroid gland

by Archan Kakadekar MD and Jason K Wasserman MD PhD FRCPC
October 20, 2022

What is an enlarged and hypercellular parathyroid gland?

The term enlarged and hypercellular parathyroid gland describes a non-cancerous growth in one or more of the parathyroid glands. Unlike the normal parathyroid glands, an enlarged and hypercellular parathyroid gland may be large enough to be felt or seen in the front of the neck.

What are the symptoms associated with an enlarged and hypercellular parathyroid gland?

Patients with an enlarged and hypercellular parathyroid gland often have symptoms associated with increased levels of calcium in the blood. Hypercalcemia means increased calcium levels in the blood and is caused by the extra parathyroid hormone produced by the enlarged gland. Symptoms of hypercalcemia include involuntary shaking (tremor), nausea, vomiting, abdominal pain, and confusion. Patients with prolonged hypercalcemia are also more likely to suffer from broken bones and kidney stones.

What causes a parathyroid gland to become enlarged and hypercellular?

The cause of an enlarged and hypercellular parathyroid gland depends on the number of glands involved. For example, genetic factors are more likely to play a role when only a single gland is enlarged. A single enlarged gland is called a parathyroid adenoma. In contrast, multiple enlarged glands are typically caused by long-standing medical conditions such as chronic kidney disease. Multiple enlarged glands are described as parathyroid hyperplasia.

Parathyroid adenoma

A parathyroid adenoma is a non-cancerous type of parathyroid gland tumour and the most common cause of a condition called primary hyperparathyroidism. Parathyroid adenomas are often sporadic which means doctors do not know what causes them. However, some genetic syndromes such as multiple endocrine neoplasia (MEN) and familial isolated hyperparathyroidism (FIHP), greatly increase a person’s risk for developing these tumours.

Parathyroid hyperplasia

If more than one parathyroid gland is involved, the condition is described as parathyroid hyperplasia. This condition frequently develops in people with chronic kidney disease and is the most common cause of secondary hyperparathyroidism. In this situation, the parathyroid glands may return to normal after treatment improves kidney function. A single enlarged and hypercellular parathyroid gland that remains after treatment is described as tertiary hyperparathyroidism.

How is this diagnosis made?

The diagnosis is made after one or more parathyroid glands are surgically removed and the tissue is sent to a pathologist for examination under the microscope.