Most people have four parathyroid glands, which sit behind the thyroid gland in the neck.
They produce parathyroid hormone (PTH), which helps control the body's calcium levels.
Overproduction of PTH (hyperparathyroidism) is the most common reason to need parathyroid surgery.
It is usually a condition in which one or more parathyroid glands become enlarged and produce too much PTH, leading to high levels of calcium, which in turn can cause various symptoms.
Investigations such as an ultrasound, and sestamibi scan can help to identify which of the four glands is responsible.
Minimally invasive parathyroidectomy involves an incision over the problem parathyroid, occasionally requiring further dissection in the neck.