Hyperparathyroidism

The parathyroid glands are four small glands found at the back of the thyroid gland in the neck. The parathyroid glands are responsible for secreting the parathyroid hormone (PTH) into the bloodstream. Hyperparathyroidism is when these glands are too active and secrete more PTH than is healthy.

PTH is responsible for regulating the level of calcium in the bones and bloodstream. When there is too much PTH, calcium is drawn (leached) out of the bones, into the bloodstream and removed by the kidneys. The imbalance of calcium can cause a range of problems, although most people with too much PTH are not aware of their condition.

Hyperparathyroidism is diagnosed in about one of every 1000 men and 2-3 of every 1000 women.

The parathyroid glands, located at the back of the thyroid gland, secrete parathyroid hormone. 

Causes and types

Primary hyperparathyroidism

This is when a problem with the parathyroid gland itself makes it secrete too much PTH. The most common causes of this is a benign (non-cancerous) tumor (known as an adenoma) in one or more of the parathyroid glands.

In 75-85% of cases, only one gland develops an adenoma. In uncommon cases, all four parathyroid glands are enlarged and over-secreting (a condition known as parathyroid hyperplasia). In rare cases, only two of the glands are enlarged.

Very rarely, the tumor is not benign, but cancerous (parathyroid cancer).

There are also some cases in which additional parathyroid glands are found in the thyroid area (or, rarely, elsewhere in the body). These can sometimes be the cause of hyperparathyroidism.

Secondary hyperparathyroidism

When a problem in the body, such as chronic kidney problems or vitamin D deficiency, lowers blood calcium levels, the parathyroid gland secretes more PTH.

Secondary hyperparathyroidism is not a medical problem, but a normal response of the body.

Tertiary hyperparathyroidism

When secondary hyperparathyroidism has gone on for a long time, the body has become used to secreting a lot of PTH. The parathyroid glands compensate by secreting too much PTH.

Parathyroid crisis

Also known as 'parathyroid storm', this is a rare medical emergency. It is a complication of primary hyperparathyroidism and is usually associated with a parathyroid cancer, in which blood calcium levels become several times higher than normal. It has serious effects on the brain and nervous system, and requires immediate surgical intervention.

Signs and symptoms

The symptoms of hyperparathyroidism are not easy to detect. Many people with high PTH levels show no symptoms at all, or only mild ones, for a long time.

People with hyperparathyroidism often believe they are feeling fine, but after they are treated, they feel better - their sleep and thinking improve.

Symptoms include:

• Kidney stones;
• Bone, joint and muscle pain;
• Increased risk of fractures;
• Fractures that happen for no reason (no fall or injury);
• Thirst;
• Frequent urination (peeing);
• Stomach pain;
• Constipation;
• Nausea;
• Loss of appetite;
• Confusion and difficulty with memory and concentration;
• Depression;
• Weakness, fatigue, and;
• High blood pressure (hypertension).

A mnemonic for symptoms of hyperparathyroidism is 'moans, groans, bones and stones', as they include symptoms of bone aches, kidney stones, stomach pains (moans) and mental changes (groans).

Methods for diagnosis

Hyperparathyroidism is diagnosed based on blood test results and symptoms. Your doctor will look for high calcium levels in your blood, low bone density, and calcium build-up in your kidneys (kidney stones).

Because it often shows no symptoms, hyperparathyroidism is most often diagnosed in blood tests that are taken for other purposes.

Types of treatment

Monitoring

If your blood calcium levels are just a little higher than normal, there might be no reason for treatment. In that case, your doctor will suggest monitoring your blood calcium and bone density regularly, and ways you can lower the risk of developing hyperparathyroidism (see the 'Prevention' section below).

Surgery

Surgical removal of the parathyroid gland (parathyroidectomy) is the most effective treatment for hyperparathyroidism. It has a high success rate (95%) and a low chance of complications.

Medication

In cases where surgery is not possible or not recommended, there are medications that can help treat hyperparathyroidism. Bisphosphonates, such as alendronate, help slow the leaching of calcium from bones.

Potential complications

As calcium levels rise, the symptoms listed above become progressively worse. Common complications include:

• Kidney stones, kidney failure;
• Cognitive problems - fatigue, concentration and memory problems, confusion;
• Bone damage, such as osteoporosis;
• Pancreatitis, and;
• Heart problems, such as atrial fibrillation and palpitations.

Prognosis

With treatment, hyperparathyroidism can be successfully cured. The health of bones can improve and the risk of future fractures decreases, but the rate of improvement depends on your age and other medical conditions.

Prevention

There is not much you can do to prevent hyperparathyroidism, other than being vigilant to the appearance of symptoms. People who are at risk, or have already been diagnosed with mild hyperparathyroidism with no symptoms, can make sure they get enough physical activity and drink enough fluids. They can also watch their calcium and vitamin D intake, making sure that the levels of these two are in the recommended range.