Hyperparathyroidism is a condition that occurs when the parathyroid glands produce more parathyroid hormone than is needed. There are four parathyroid glands in total, which are small, located in the neck and sit just behind the thyroid gland.
Parathyroid hormone is in charge of controlling the levels of phosphate and calcium in the blood. It is usually released when the levels of calcium in the blood are high. However, once they have returned to the usual levels the hormone is no longer released. In people who have hyperparathyroidism excessive parathyroid hormone is released and this causes calcium levels to be higher than normal.
About parathyroid hormone
Parathyroid hormone has several important roles in the body, which include:
- Facilitating the absorption of calcium from the intestine.
- Prompting the exit of calcium from the bones.
- Causing the kidneys to release phosphate into the urine.
- Preventing the kidneys from excreting calcium into the urine.
It is important for the sums of calcium and phosphate to be controlled and regulated. Calcium and phosphate come together to make calcium phosphate, which is used to strengthen the bones. Calcium is also an important component of the clotting system, which kicks into action following an injury and causes bleeding. It is also of importance for effective muscle and nerve function. Phosphate is also involved in many of these functions and processes and is also vital for producing energy in the body.
What causes Hyperparathyroidism?
There are various types of hyperparathyroidism and they are classified as primary, secondary and tertiary hyperparathyroidism.
In people with primary hyperparathyroidism, a single or more of the parathyroid glands is enlarged and produces more parathyroid hormone than is required, which causes calcium levels to become higher than normal. Causes of primary hyperparathyroidism include:
- Parathyroid adenoma: this is a non-cancerous (benign) tumour that develops in one of the parathyroid glands.
- Hyperplasia: hyperplasia can affect one or additional parathyroid glands and means that the gland is enlarged and producing more parathyroid hormone than normal. Usually more than a single gland is affected.
- Carcinoma: in rare cases hyperparathyroidism is brought on by a carcinoma (cancerous cells) in one of the glands.
It is not known what causes most cases of primary hyperparathyroidism; however, there is a higher danger of developing the condition if you have had treatment for cancer beforehand. It is unusual for hyperparathyroidism to be passed on in families, but some cases are caused by a rare inherited illness known as familial isolated hyperparathyroidism. It is also possible for an individual to develop the condition as a result of having a syndrome called multiple endocrine neoplasia. This condition affects the pituitary and parathyroid glands and the pancreas.
Secondary hyperparathyroidism is brought about by other health conditions or deficiencies in the body. Possible causes include:
- Kidney disease: almost all individuals who rely on kidney dialysis suffer from hyperparathyroidism, causing calcium levels in the blood to be low. It is most often the cause of the condition.
- Deficiency of vitamin D: a deficiency of vitamin D causes chronic low levels of calcium in the blood.
- Malabsorption: many conditions can affect absorption from the gut and avert the absorption of calcium into the bloodstream.
Tertiary hyperparathyroidism develops as a consequence of long-term secondary hyperparathyroidism. In such cases treatment for the cause of hyperparathyroidism, but the parathyroid glands are still producing too much parathyroid hormone because they run autonomously rather than responding to the amount of calcium in the blood. This form of hyperparathyroidism is seen most commonly in people who have kidney failure.
Symptoms of Hyperparathyroidism
In many cases of primary hyperparathyroidism no symptoms are present and many people are diagnosed with the condition as a result of the blood tests they are having for other conditions. If you experience symptoms and you have either primary or tertiary hyperparathyroidism, this is due to an elevated level of calcium in the blood. Symptoms include:
- Feeling thirsty.
- Urinating more regularly than usual.
- Feeling weak.
- Abdominal pain.
- Muscle weakness.
- Depression or feeling low.
If levels of calcium are high and an individual does not receive treatment this can increase the risk of complications, including:
- Irregular heart rhythms.
- Loss of consciousness.
In extreme cases the condition can be fatal.
Complications of Hyperparathyroidism
Possible complications of high levels of calcium in the blood (primary and tertiary hyperparathyroidism) include:
- Kidney stones.
- Peptic ulcers.
- Damage to the kidneys.
All forms of hyperparathyroidism can contribute to thinning of the bones, known as osteopenia.
How is Hyperparathyroidism diagnosed?
If your doctor suspects that you have hyperparathyroidism they will refer you for tests. Blood tests are carried out to measure the levels of calcium and phosphate in the blood and the quantity of parathyroid hormone. If the levels of calcium and parathyroid hormone are high and the level of phosphate is low, this usually indicates that you have hyperparathyroidism. Often blood tests are ordered as a result of complications of hyperparathyroidism, such as kidney stones. If you have a high level of parathyroid hormone and a low level of calcium in your blood, this may indicate that you have secondary hyperparathyroidism. In people with kidney disease the level of phosphate may also be high as a result of the kidneys being unable to excrete phosphate into the urine.
Further tests may be carried out to determine the form of hyperparathyroidism and the cause, as they may also be carried out to check for complications:
- Further blood tests.
- CT scan.
- Ultrasound scan of the kidneys.
- Urine test (to calculate the sum of calcium).
- DEXA scan to check bone density.
- Biopsy sample of the parathyroid gland.
There are various treatment options for hyperparathyroidism, including:
- Watchful waiting: if you do not have symptoms and your calcium levels are only slightly higher than normal, your doctor may agree to monitor your illness rather than recommending immediate treatment. You will then be advised to have regular tests, including blood tests, blood pressure checks and kidney function tests.
- Surgery: surgery can be carried out to take out the affected gland or glands. After surgery your calcium levels will be monitored closely. It is possible for a number of the glands to be removed, but at least half of one of the glands will usually be kept in place. Surgery to remove the parathyroid gland is known as a parathyroidectomy.
- Medication: in some cases surgery is not recommended, so medication is used to try and reduce levels of calcium in the blood and prevent thinning of the bones. There are different types of drugs that are used, including bisphosphonates.
It is important for secondary hyperparathyroidism to be treated early to prevent damage to the bones. The underlying cause of the condition will be treated as a priority. Most cases of secondary hyperparathyroidism are caused by kidney disease. Possible treatments for kidney disease include:
- Increasing calcium levels by taking vitamin D and calcium supplements.
- Taking a drug called cinacalet, which reduces the total of parathyroid hormone released by the parathyroid glands.
- Decreasing blood phosphate levels, able to be done by restricting your intake of dairy foods and taking medication.
If a patient doesn’t respond to the treatments listed above and their condition is severe, they may be advised to have surgery to remove the affected parathyroid glands.
In most cases surgery is used to get rid of the abnormal gland or glands. If all the glands are affected a small amount of parathyroid tissue may be implanted into the arm to control calcium levels.
If you have hyperparathyroidism there are some things you can do to help yourself, which includes:
- Drinking plenty of water.
- See a doctor as soon as possible if you feel unwell.
- Avoid taking diuretics.
Complications of surgery
It is uncommon to experience complications after surgery, though it is possible. Possible complications of parathyroid surgery include:
- Low calcium levels (hypocalcaemia).
- Harm to the nerves in the neck.
Outlook for Hyperparathyroidism
In most cases, if primary hyperparathyroidism is diagnosed early and treated effectively, the prognosis is positive. However, the outlook for secondary and tertiary hyperparathyroidism is not as good.