Hypoparathyroidism and hyperparathyroidism are rare hormone disorders caused by the parathyroid glands in the neck producing too little (hypo) or too much (hyper) parathyroid hormone.
You have four tiny parathyroid glands, each the size of a grain of rice, in your neck behind the thyroid gland. They produce parathyroid hormone (PTH) to help control the levels of calcium, phosphorus and vitamin D within the bones and blood.
This is important, as these levels can naturally fluctuate and need to be kept within a healthy range for the body to function properly. For example, calcium levels can rise if you eat a dairy-rich meal, and can fall if you take certain medication.
Read more about why our bodies need calcium and why we need phosphorus.
The parathyroid glands are nothing to do with the thyroid gland. 'Parathyroid' means 'near the thyroid'. Parathyroid disorders should not be confused with an underactive thyroid or overactive thyroid.
This page explains the symptoms, causes, diagnosis, treatment and possible complications of both hypoparathyroidism and hyperparathyroidism.
Hypoparathyroidism means the parathyroid glands produce too little PTH. This causes blood calcium levels to fall (hypocalcaemia) and blood phosphorus levels to rise (hyperphosphataemia).
You may need to take supplements for life to restore these levels. Read more about treatments for hypoparathyroidism.
The symptoms of hypoparathyroidism vary depending on the cause, the speed at which the condition develops and the effectiveness of treatment.
People who develop hypoparathyroidism quickly (for example, after neck surgery) can have the following symptoms:
- a tingling sensation in the hands or feet or around the mouth (paraesthesia)
- unusual muscle movements, such as jerking, twitching or muscle spasms
- muscle cramps
- feeling tired, irritable, anxious or depressed
People with long-lasting (and gradually developing) hypoparathyroidism caused by other medical conditions can have:
- the above symptoms, if untreated
- eye problems, especially cataracts
- dry, thick skin
- coarse hair that breaks easily and can fall out
- fingernails that break easily, with ridges that go from left to right
In theory, very low calcium can cause fits, but this is very rare, especially if you've had the condition for some time and are being treated with medication.
Often, anxiety can cause you to breathe rapidly (hyperventilate). This could make you feel ill and make your calcium drop even further, so it's important to remain calm.
The most common cause of hypoparathyroidism is accidental injury to the parathyroid glands during head and neck surgery. In about 12% of patients undergoing surgery it lasts for only a short time. Fewer than 3% of patients have permanent hypoparathyroidism.
Other causes include:
- destruction of the parathyroid glands by the immune system in people with autoimmune diseases, where the body mistakenly attacks its own tissues
- radiation therapy to the neck for cancer
- surgical removal of the parathyroid glands because of cancer
- low blood magnesium levels, for example from alcoholism
Who is affected
You are more likely to develop hypoparathyroidism if you:
- have had recent thyroid or neck surgery
- have a family history of parathyroid disorder
- have Addison's disease (a rare disorder of the adrenal glands above the kidneys)
Also, children or adults with the inherited disease DiGeorge syndrome will have hypoparathyroidism because their parathyroid glands are missing at birth.
Hypoparathyroidism is diagnosed after a blood test shows:
- low blood calcium levels
- high blood phosphorus levels
- low blood PTH levels
If you have hypoparathyroidism an electrocardiogram (ECG) may show abnormal heart rhythms and a urine test will show high levels of urinary calcium (too much calcium leaving the body).
Treatment aims to bring the blood levels of calcium and other minerals back to normal.
The normal calcium range is around 2.10–2.50 millimoles per litre (mmol/L). You should aim to maintain your blood calcium levels at 2.00–2.25 mmol/L.
Calcium carbonate and vitamin D supplements – usually calcitriol (Rocaltrol) or alfacalcidol (One-Alpha) – can be taken to restore these levels. Except for patients who have short-lived hypoparathyroidism after neck surgery, these normally have to be taken for life. Your blood levels will need to be continuously monitored with regular blood tests. The aim of therapy is to relieve symptoms and keep calcium in the near-normal or low-normal range.
It's also recommended that you follow a high-calcium, low-phosphorus diet.
Good sources of calcium include:
- milk, cheese and other dairy foods
- green leafy vegetables, such as broccoli, cabbage and okra, but not spinach
- soya beans
- soya drinks with added calcium
- bread and anything made with fortified flour
- fish where you eat the bones, such as sardines and pilchards
Phosphorus is found in:
- red meat
- dairy foods
If your blood calcium levels drop to a dangerously low level or you keep having muscle spasms, you may need to be given calcium through a drip (directly into your vein) and your heart rhythm will be monitored until it is stable. You will then continue treatment with supplements.
Hypoparathyroidism can sometimes lead to:
- stunted growth
- poorly developed teeth
- slow mental development
Hypoparathyroidism may occur together with other autoimmune conditions such as Addison's disease and pernicious anaemia.
Excessive calcium replacement can cause complications, such as kidney stones.
Hyperparathyroidism means the parathyroid glands produce too much PTH. This causes blood calcium levels to rise (hypercalcaemia) and blood phosphorus levels to fall (hypophosphataemia).
Hyperparathyroidism does not always cause symptoms.
When high levels of calcium do cause symptoms, they can be mild or general, including:
- feeling thirsty and passing a lot of urine
- feeling sick and losing your appetite
- muscle weakness
- tummy pain
- loss of concentration
- mild confusion
But, if left untreated, high blood levels of calcium can cause:
In severe cases, high levels of calcium can lead to loss of consciousness and coma. See also the possible complications it can cause, below.
The severity of your symptoms does not always match up to the calcium level in your blood. People with only a slightly high calcium level can have severe symptoms, and vice versa.
There are two main types of hyperparathyroidism:
- Primary – when one or more of the parathyroid glands is enlarged or overactive, for reasons explained below, and the abnormality causing it is within the gland itself.
- Secondary – when nothing is wrong with the gland, but there is a disease or condition (such as kidney failure or vitamin D deficiency) that lowers calcium. The body reacts by producing too much parathyroid hormone to stop calcium levels from falling to a very low level.
Rarely, when secondary hyperparathyroidism goes untreated for too long, the gland remains overactive all the time. This is known as tertiary hyperparathyroidism. It is most commonly seen in patients who have had kidney failure for a long time.
The main cause of primary hyperparathyroidism is a non-cancerous tumour called an adenoma growing on one of the parathyroid glands, causing it to become overactive.
The other main causes of primary hyperparathyroidism are:
- two or more of the glands becoming enlarged (hyperplasia)
- radiotherapy treatment to the head or neck
Rarely, primary hyperparathyroidism may occur as a result of inherited genes and the diagnosis is made at a younger age.
Very rarely, it is caused by cancer of a parathyroid gland.
In many cases, doctors don't know the cause of hyperparathyroidism.
Who is affected
Most cases of hyperparathyroidism occur in people with no family history of the condition. Only about 5% of cases can be linked to an inherited problem.
Women are twice as likely as men to develop it and the risk increases with age.
Hyperparathyroidism is diagnosed after a blood test shows:
- high levels of PTH
- high levels of blood calcium
- low levels of phosphorus
Bone X-rays can help detect bone loss, fractures or bone softening, and X-rays, CT scans or ultrasound may show calcium deposits or a blockage.
If your hyperparathyroidism is mild, treatment may not be necessary. You may just need regular check-ups with your doctor.
You should keep to a healthy balanced diet and do not need to avoid calcium altogether. If you don't have calcium in your diet, parathyroid hormone is more likely to cause removal of calcium from the skeleton, leading to brittle bones (osteoporosis). Try to avoid a high-calcium diet and drink plenty of water to prevent dehydration.
If you have troublesome symptoms or your blood calcium is very high, you may need surgery to remove the parathyroid gland that is overproducing PTH. Surgery cures hyperparathyroidism in 95% of operations.
If surgery is not possible, you may be prescribed medication. This may be:
- Bisphosphonates to improve bone density. Very high calcium levels may need to be corrected with an intravenous drip (given directly into the vein).
- Cinacalcet to reduce your blood calcium and PTH levels and increase the phosphate levels.
Treatment of secondary hyperparathyroidism depends on the underlying cause. Read about the treatment of kidney disease, the most common cause of secondary hyperparathyroidism. Correcting the calcium level and underlying problem will usually cure the hyperparathyroidism.
Complications of hyperparathyroidism are rare, but include: