Ask an expert: What is the role of the parathyroid glands?

In this in-depth article, revered consultant endocrine surgeon Mr Ioannis Christakis gives an all-you-need-know guide to the parathyroid glands and sheds light on their role in controlling the body’s calcium levels.

What are parathyroid glands?

The parathyroid glands are small (5-6mm x 2-3mm x 1-2mm), oval-shaped and are located next to the thyroid gland. Most people have four parathyroid glands but this can vary and some people have fewer or an extra gland.

There are several types of cell which make up the parathyroid glands, including chief cells and oxyphil cells. Chief cells produce a hormone known as PTH (parathyroid hormone) and oxyphil and other types of cells secrete this hormone.

What do the parathyroid glands do?

A very important hormone known as PTH (parathyroid hormone) is produced by the parathyroid glands. PTH helps to control the levels of calcium in the blood so that they are steady, which is key as calcium is involved in many of the body’s metabolic functions.

Why is calcium so important?

Although many people know that calcium helps to build strong bones, it is also vital in many other parts of the body. Our muscles need calcium to function, including the muscles of the heart. Calcium is also key to the functioning of the brain as a neurotransmitter from cell to cell.

In order for muscles to contract and for synaptic transmission to occur in the nervous system, calcium is needed. Coagulation and hormone secretion amongst many other essential bodily processes also require calcium, therefore having sufficient levels is essential for the body to function as it should.

How do the parathyroid glands control calcium levels?

The parathyroid glands are key in controlling calcium levels. They do so by constantly measuring the levels of calcium in the blood through a special receptor in their surface. If calcium levels are low, the glands recognise this and produce more PTH. Once the levels have been balanced, the parathyroid gland picks up on this and stops making extra PTH.

What does the parathyroid hormone do?

The parathyroid hormone (PTH) affects calcium levels by promoting bone destruction, which allows calcium to be released into the blood. PTH also affects the kidneys by decreasing the amount of calcium that is lost in urine.

Vitamin D works together with the PTH to maintain steady calcium levels in the blood. Vitamin D is important as it allows calcium to be reabsorbed in the gut so it reaches the blood.

When the parathyroid glands work as they should, the body is perfectly balanced and PTH’s effects don’t cause significant damage to the bones or kidneys.

If you would like to schedule a consultation with Mr Christakis, you can do so by visiting his Top Doctors profile.