What is hypoparathyroidism?
The body has four parathyroid glands. They 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 levels of 'active' parathyroid hormone causes
calcium levels in the blood to fall and phosphate levels to rise.
Why does the body need calcium and phosphorus?
Calcium and phosphorus combine to make calcium phosphate in the body.
This is the chief 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 the
correct functioning of muscles and nerves. Phosphorus works in
conjunction with calcium for these functions. Phosphorus is also needed
for the production of energy within the body.
Who gets hypoparathyroidism?
Hypoparathyroidism is rare. It occurs equally in males and females. The
age that someone may develop hypoparathyroidism depends on its cause.
What causes hypoparathyroidism?
Hypoparathyroidism can be:
- Transient (short-lived).
- Congenital (something that someone, for some reason, is born with).
- Inherited (passed on through your genes from your relatives).
- Acquired (something that develops in childhood or adult life for another reason).
- Pseudohypoparathyroidism.
- Pseudopseudohypoparathyroidism.
Transient hypoparathyroidism
- This most
commonly occurs in babies who are born prematurely. It can also occur
in otherwise healthy babies born at the normal time. It is due to
failure of parathyroid hormone to be released from the parathyroid
glands normally after birth.
- Transient hypoparathyroidism can also affect babies born to mothers
who have diabetes or to mothers who have overactive parathyroid glands.
Congenital hypoparathyroidism
- DiGeorge
syndrome. This is a congenital condition where the parathyroid glands
do not develop properly while the baby is growing in the uterus (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 part of another syndrome
(a collection of problems). An example is hypoparathyroidism that
occurs with deafness and also problems with kidney development.
Inherited hypoparathyroidism
- 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 "germs" causing the infection. In autoimmune
diseases the body makes similar antibodies (autoantibodies) that attack
its normal cells. In autoimmune hypoparathyroidism, these
autoantibodies attack the cells of the parathyroid glands. Autoimmune
hypoparathyroidism can exist alone, or as part of a syndrome of
problems 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.
Acquired hypoparathyroidism
- The most
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. The parathyroid glands
may also be intentionally removed because of potential malignancy
(cancer), or as a treatment for hyperparathyroidism (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
drugs 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 in turn
causes a reduction in parathyroid hormone release and
hypoparathyroidism.
- Acquired hypoparathyroidism can also occur due to an acquired
autoimmune condition. For some reason, autoantibodies start attacking
the cells of the parathyroid glands and destroying them, as described
above.
Pseudohypoparathyroidism
This is a rare
disorder that is inherited. Parathyroid hormone is present in the body
but the body is unable to respond normally to it. There are low calcium
levels 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.
Pseudopseudohypoparathyroidism
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?
Individuals
can experience different symptoms of hypoparathyroidism in different
ways. The symptoms are largley 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 needing urgent treatment
with calcium given intravenously (directly into the veins via a drip).
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).
- Seizures.
- Fainting.
- Confusion.
- Memory problems.
- Tiredness.
- Eyesight problems.
- Headaches.
- Brittle nails.
- Dry skin and hair.
- Painful menstruation (periods).
Are there any complications of hypoparathyroidism?
Any
complications that may arise because of hypoparathyroidism are largely
due to the low levels of calcium that it causes in the body.
Complications can include:
- Kidney stones.
- Cataracts.
- 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?
Physical examination
There are a number of
things that your doctor may look for when they examine you if they
suspect that you have hypoparathyroidism:
- They may tap in
front of your ear with your mouth slightly open. If your calcium levels
are 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 levels are 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 levels are low due to
hypoparathyroidism, these reflexes can be much more forceful than
normal.
Blood tests
Your doctor will suggest some
blood tests to 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 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 for hypoparathyroidism?
The
aims of treatment are to ensure that there are adequate levels of
calcium in the bloodstream. This should mean that you will not suffer
from any of the symptoms associated with low calcium levels.
What are the treatment options for hypoparathyroidism?
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 intestine and the kidneys.
Regular blood tests are needed to ensure that you are taking adequate
amounts of calcium and vitamin D. Closer monitoring is needed during
pregnancy, if you are also taking other drugs, or if you are also
suffering from another illness. Treatment is usually lifelong. These
are not dietary supplements that you can buy over-the-counter, but more
potent medication requiring careful monitoring by your doctor.
Intravenous calcium
If you experience severe
symptoms of low calcium levels, you may need treatment with intravenous
calcium (the calcium is given directly into a vein via a drip).
Diet
A diet rich in calcium and vitamin D is also recommended.
Other treatments
There are other possible
treatments for hypoparathyroidism. If someone is having surgery to
remove their 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 prognosis (outlook) of hypoparathyroidism?
If
hypoparathyroidism is adequately treated with calcium and vitamin D,
the prognosis the prognosis is good. However, a good prognosis relies
on the person who is affected taking their medication daily for life
and also having regular blood tests so that the dose of their
medication can be carefully adjusted as needed.
Can hypoparathyroidism be prevented?
During
thyroid or neck surgery, care must be taken by the surgeon to identify
and locate the parathyroid glands and to avoid damage to them if
possible. Anybody who is undergoing thyroid or neck surgery,
radiotherapy to the neck or the chest, or chemotherapy (drug treatment
for cancer) should be monitored for symptoms and signs of low calcium
levels.
Another point about hypoparathyroidism
You
should wear a MedicAlert® bracelet, or carry some kind of ID with you,
to identify yourself as suffering from hypoparathyroidism. This is so
that if you collapse, are confused or are found unconscious, doctors
will know that you need treatment with calcium. Please refer to the
information below for details.
Further help and information
MedicAlert
1 Bridge Wharf, 156 Caledonian Road, London, N1 9UU
Freephone: 0800 581420 Web: www.medicalert.co.uk
A registered charity providing a life-saving identification system to protect and save lives.
Hypoparathyroidism UK (HPTH UK)
6 The Meads, East Grinstead, West Sussex, RH19 4DF
Web: www.hpth.org.uk
A voluntary organisation committed to improving the lives of people with hypoparathyroidism and other parathyroid disorders.
References
-
Thornton PS, Kelly A, Willcutts M; Hypoparathyroidism; eMedicine (July 2006); (Paediatric slanted article)
-
Understanding the causes of Hypoparathyroidism, Hypoparathyroidism UK. Information obtained from website in October 2007.
- J.
A. Kanis. Disorders of calcium metabolism, Hypoparathyroidism. Chapter
7.5.2. Concise Oxford Textbook of Medicine First edition - April 2000
-
Winer KK, Ko CW, Reynolds JC, et al;
Long-term treatment of hypoparathyroidism: a randomized controlled
study comparing parathyroid hormone-(1-34) versus calcitriol and
calcium. J Clin Endocrinol Metab. 2003 Sep;88(9):4214-20. [abstract]
© EMIS and PiP 2007 Updated: 22 Oct 2007
