Parathyroid

What are the parathyroid glands?

The parathyroid glands are four pea-sized glands located on the thyroid gland in the neck – though their names are similar, the thyroid and parathyroid glands are entirely different glands, each producing distinct hormones with specific functions
The glands secrete PTH, a hormone that helps maintain the correct balance of calcium and phosphorus in the body
PTH regulates the level of calcium in the blood, release of calcium from bone, absorption of calcium in the intestine, and excretion of calcium in the urine – when the level of calcium in the blood falls too low, the parathyroid glands secrete just enough PTH to restore the blood calcium level
As blood flows through the parathyroid glands, the amount of calcium and Vitamin D in the blood is checked and if the amount of calcium or Vitamin D is low the gland produces PTH, and if the amount of calcium is high the gland stops producing PTH
Through this mechanism, there is minute-to-minute control of the level of calcium in the blood – the concentration of calcium in the blood is very important to normal functioning of the body and this is why there are four glands, even though one gland would be enough to do the job

Excess PTH triggers:
- The release of too much calcium into the bloodstream
- The bones may lose calcium
- Too much calcium may be absorbed from food
- The levels of calcium may increase in the urine, causing kidney stones.
- PTH also lowers blood phosphorus levels by increasing excretion of phosphorus in the urine

Calcium is essential for good health – it plays an important role in bone and tooth development and in maintaining bone strength
Calcium is also important in nerve transmission and muscle contraction
Phosphorus is found in all bodily tissue – it is a main part of every cell with many roles and combined with calcium, phosphorus gives strength and rigidity to your bones and teeth

Hyperparathyroidism is a condition in which the parathyroid gland makes more of the PTH than it needs, causing an imbalance in the amount of calcium in the body – this can lead to problems with the bones, muscles, nervous system, and kidneys
Hyperparathyroidism is caused by inappropriately increased secretion of parathyroid hormone (PTH)
If the glands secrete too much hormone (PTH), the balance is disrupted and the blood calcium level rises
This condition of excessive calcium in the blood, called hypercalcaemia, is the first sign that something may be wrong with the parathyroid glands

Primary hyperparathyroidism is a disorder of the parathyroid glands
“Primary” means this disorder originates in the parathyroids: One or more enlarged, overactive gland secretes too much parathyroid hormone (PTH), inappropriate to the serum calcium level

The vast majority of cases occur in people with no family history of the disorder – only about 5 % of cases can be linked to an inherited problem
In 85 % of people with primary hyperparathyroidism, a benign tumour called an adenoma has formed on one of the parathyroid glands, causing it to become overactive
In most other cases, the excess hormone comes from two or more enlarged glands, a condition called hyperplasia – very rarely, hyperparathyroidism is caused by cancer of a parathyroid gland

Women outnumber men two to one, and the risk increases with age
In women 60 years and older, two out of 1,000 people will develop hyperparathyroidism each year

A person with hyperparathyroidism may have severe symptoms, subtle ones, or none at all
The commonest finding is an elevated calcium level on a routine blood test
Patients may have thinning of the bones without symptoms
When symptoms do appear, they are often mild and nonspecific, such as a feeling of weakness and fatigue, depression, or aches and pains
With more severe disease, a person may have a loss of appetite, nausea, vomiting, constipation, confusion or impaired thinking and memory, and increased thirst and urination
Increased calcium and phosphorus excretion in the urine may cause kidney stones

Hyperparathyroidism is diagnosed when tests show that blood levels of calcium and parathyroid hormone are too high
Other diseases can cause high blood calcium levels, but only in hyperparathyroidism is the elevated calcium the result of too much parathyroid hormone
A blood test that accurately measures the amount of parathyroid hormone has simplified the diagnosis of hyperparathyroidism
Once the diagnosis is established, other tests may be done to assess complications – because high PTH levels can cause bones to weaken from calcium loss, a measurement of bone density can help assess bone loss and the risk of fractures

Surgery to remove the enlarged gland (or glands) is the main treatment for the disorder and cures it in 95 percent of operations
Surgery may be a minimally invasive parathyroidectomy procedure or an open parathyroidectomy
Some patients who have mild disease may not need immediate treatment

In secondary hyperparathyroidism, the stimulus is chronically low serum calcium levels
A problem such as kidney failure or malabsorbtion syndromes leads to a low calcium level which in turn causes the parathyroids to be overactive
All four glands become enlarged (hyperplastic)
Treatment requires oral calcium supplements and reducing plasma phosphate levels with oral aluminium hydroxide

Tertiary hyperparathyroidism is a consequence of secondary hyperparathyroidism.
This usually occurs due to an adenoma and treatment is with open parathyroidectomy

Surgery for hyperparathyroidism is highly successful with a low complication rate
About 1 percent of patients undergoing surgery experience damage to the nerves controlling the vocal cords, which can affect speech
One to 5 percent of patients lose all their parathyroid tissue and thus develop low calcium levels, which may require treatment with calcium or vitamin D – the complication rate is slightly higher for hyperplasia than it is for adenoma since more extensive surgery is needed