Parathyroid - Underactive
Hypoparathyroidism occurs when too little parathyroid hormone is released by the parathyroid glands, or the parathyroid hormone that is released does not work properly. Either leads to low levels of calcium in the blood, which can cause a number of different symptoms. The most common are muscle cramps, pain and twitching. Hypoparathyroidism can be successfully treated with calcium and vitamin D supplements but regular blood test monitoring is needed.
What is hypoparathyroidism?
The four parathyroid glands are small, pea-sized glands, located in the neck just behind the butterfly-shaped thyroid gland. Two parathyroid glands lie behind each wing of the thyroid gland.
The parathyroid glands release a hormone called parathyroid hormone. This hormone helps to control the levels of two salts in the body: calcium and phosphorus.
Hypoparathyroidism occurs when either:
- The parathyroid glands do not release enough parathyroid hormone, or
- The parathyroid hormone that is released does not work properly.
The resulting low level of active parathyroid hormone causes the calcium level in the blood to fall and the phosphate level to rise.
Why does the body need calcium and phosphorus?
Calcium and phosphorus combine to make calcium phosphate in the body. This is the main material that gives hardness and strength to bones and teeth. Calcium is also needed as part of the complex mechanism that helps blood to clot after an injury. It is also required for muscles and nerves to work properly. Phosphorus works with calcium to do these jobs. Phosphorus is also needed for the production of energy within the body.
Who gets hypoparathyroidism?
Hypoparathyroidism is rare. Men and women are equally likely to have the problem. The age that someone may develop hypoparathyroidism depends on its cause.
What causes hypoparathyroidism?
Hypoparathyroidism can be:
- Acquired (something that develops in childhood or adult life).
- Transient (short-lived).
- Congenital (something that someone is born with).
- Inherited (passed on through your genes, from your relatives).
- Pseudohypoparathyroidism. Pseudo means false. In these cases, the illness seems to be hypoparathyroidism, but isn't. See below.
- The common cause of acquired hypoparathyroidism is after surgery to the neck. For example, during surgery on the thyroid gland, the parathyroid glands may be accidentally damaged or removed. Sometimes the parathyroid glands are removed because of potential cancer, or as a treatment for overactive parathyroid glands.
- Radiotherapy treatment (because of a cancer in the neck or the chest) can damage the parathyroid glands and make them underactive. Certain medicines used in the treatment of cancers can do the same.
- The parathyroid glands can also become replaced and destroyed by cancer cells, spreading from cancer elsewhere in the body. This causes a reduction in parathyroid hormone release and hypoparathyroidism.
- Acquired hypoparathyroidism can also occur due to an acquired autoimmune condition. Auto-antibodies may start attacking the cells of the parathyroid glands and destroy them, as described below.
- This occurs most commonly in babies who are born prematurely (too soon). It can also occur in otherwise healthy babies born at the normal time. Parathyroid hormone is there in the glands but isn't released normally after the baby is born. It is eventually released and all returns to normal.
- Transient hypoparathyroidism can also affect babies of mothers who have diabetes, or babies born to mothers who have overactive parathyroid glands.
- DiGeorge's syndrome. This is a congenital condition - you are born with it. The parathyroid glands do not develop properly while the baby is growing in the womb. People with this syndrome have hypoparathyroidism. Also, their immune system does not work properly and they may have heart problems and a cleft palate (problems with the development of the roof of their mouth).
- Congenital hypoparathyroidism can also be one of a number of problems (a syndrome). One example is hypoparathyroidism that occurs with deafness and problems with kidney development. Most syndromes have unusual names.
- Hypoparathyroidism may be caused by an inherited autoimmune problem. Normally, our body makes antibodies to fight infections - for example, when we catch a cold or have a sore throat. These antibodies help to kill the cells of the bacteria, viruses or other germs causing the infection. In autoimmune diseases the body makes similar antibodies (auto-antibodies) that attack its normal cells. In autoimmune hypoparathyroidism, these auto-antibodies attack the cells of the parathyroid glands. Autoimmune hypoparathyroidism can exist alone, or as part of a syndrome including diabetes and thyroid gland disease.
- Inherited hypoparathyroidism can also be caused by inherited problems with the gene that is needed for the body to make parathyroid hormone. This means that the gene does not function properly which leads to a lack of parathyroid hormone.
This is a rare disorder that is inherited. Parathyroid hormone is present in the body but the body is unable to respond to it normally. There is a low calcium level in the blood. Affected people are short and have shortened bones in their feet and hands. They may also have diabetes and an underactive thyroid gland.
This is when someone has the features of pseudohypoparathyroidism, as described above, but they have normal calcium and phosphate levels in the blood.
What are the symptoms of hypoparathyroidism?
People experience the different symptoms of hypoparathyroidism in different ways. The symptoms are largely due to the effects of low levels of calcium in the blood.
Mild symptoms usually develop slowly and may be fleeting or they may require a small adjustment in medication (see below). Severe symptoms may come on rapidly and need urgent treatment. This may be with calcium given directly into the vein via a drip (intravenously).
Possible symptoms that may occur include:
- Muscle pains.
- Abdominal (stomach) pains.
- Tingling, vibrating, burning or numbness of the fingers, toes or face.
- Twitching of the muscles of the face.
- Carpopedal spasm (contraction, or tightening, of the muscles of the hands and feet).
- Memory problems.
- Eyesight problems.
- Brittle nails.
- Dry skin and hair.
- Painful periods.
Are there any complications of hypoparathyroidism?
Any complications that may arise are largely due to the low levels of calcium in the body. Complications can include:
- Kidney stones.
- Disturbance of the normal electrical activity of the heart. This can lead to irregularities in the heart rhythm which can in turn lead to collapse.
- Stunted growth, teeth problems and problems with mental development can occur if low calcium levels are not treated in childhood.
How is hypoparathyroidism diagnosed?
There are a number of things that your doctor may look for when they examine you:
- They may tap in front of your ear with your mouth slightly open. If your calcium level is low because of hypoparathyroidism, this can cause repeated contraction (tightening) of the muscles in your face. This is called Chvostek's sign.
- Your doctor may also inflate a blood pressure cuff around the lower part of your arm. If your calcium level is low because of hypoparathyroidism, this can lead to carpopedal spasm, as described above.
- They may examine your eyes to look for cataracts which can be a complication of hypoparathyroidism.
- They may examine your muscle reflexes. This is a painless examination done by tapping the tendons of the muscles - for example, at the knee or the elbow. It is done using a special instrument called a tendon hammer. If your calcium level is low due to hypoparathyroidism, these reflexes can be much more forceful than normal.
Blood tests can confirm hypoparathyroidism. In hypoparathyroidism, your blood calcium level is low, your blood phosphate level is high, and your parathyroid hormone level is low.
If your doctor suspects that your hypoparathyroidism is caused by an autoimmune process, they may suggest some other blood tests. For example, they may want to look at your thyroid gland to check that this is not also affected.
Other possible investigations
Your doctor may suggest some other tests to look for the cause of your hypoparathyroidism. For example:
- Hand X-rays - to look for the shortened bones seen in pseudohypoparathyroidism.
- Echocardiogram (an ultrasound scan of the heart) - to look for heart abnormalities associated with DiGeorge's syndrome.
- Genetic studies - special blood tests can be performed if your doctor suspects that you have an inherited cause for your hypoparathyroidism.
What are the aims of treatment?
The aims of treatment are to ensure that there is an adequate level of calcium in the bloodstream. This should mean that you will not have symptoms associated with low calcium levels.
What are the treatment options?
Calcium and vitamin D supplements
Hypoparathyroidism is treated with calcium and vitamin D supplements taken by mouth. Vitamin D supplements are needed because vitamin D also helps to regulate calcium levels. It stimulates the release of calcium from bone and helps calcium to be absorbed from the gut and the kidneys. Regular blood tests are needed to ensure that you are taking enough calcium and vitamin D. Closer monitoring is needed during pregnancy, if you are also taking other medicines, or if you also have another illness. Treatment is usually lifelong. These are not dietary supplements that you can buy over-the-counter, but stronger medication requiring careful monitoring by your doctor.
If you have severe symptoms, you may need calcium given directly into your vein via a drip (intravenously).
A diet rich in calcium and vitamin D is also recommended.
There are other possible treatments for hypoparathyroidism. For example, if you have surgery to remove your thyroid gland, one of the parathyroid glands may be transplanted (or moved) and re-sited in the neck or the arm. This means that it can continue to release parathyroid hormone. There have also been trials carried out where people with hypoparathyroidism have been given parathyroid hormone that has been made synthetically. However, synthetic parathyroid hormone is not currently licensed to treat people with hypoparathyroidism in the UK.
What is the outlook?
If hypoparathyroidism is adequately treated with calcium and vitamin D, the prognosis is good. However, this relies on you taking medication daily for life. You also need to have regular blood tests so that the dose of your medication can be carefully adjusted as needed.
Can hypoparathyroidism be prevented?
During thyroid or neck surgery, the surgeon must identify the parathyroid glands and avoid damaging them if possible. Anybody who is undergoing thyroid or neck surgery, radiotherapy to the neck or the chest, or chemotherapy (a treatment for cancer) should be monitored for symptoms and signs of low calcium levels.
Another point about hypoparathyroidism
You should consider wearing a MedicAlert® bracelet (or similar), or carry some kind of ID with you, to identify yourself as having hypoparathyroidism. This is so that if you collapse, are confused or are found unconscious, doctors will know that you need prompt treatment with calcium.
Further help and information
Hypoparathyroidism UK (HPTH UK)
6 The Meads, East Grinstead, West Sussex, RH19 4DF