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Primary hyperparathyroidism is a disorder of the parathyroid glands, also
called parathyroids. “Primary” means this disorder originates in the
parathyroids: One or more enlarged, overactive parathyroid glands secretes too
much parathyroid hormone (PTH). In secondary hyperparathyroidism, a problem such
as kidney failure causes the parathyroids to be overactive. This publication
focuses on primary hyperparathyroidism.
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What are the parathyroid glands?
The parathyroid glands are four pea-sized glands located on the thyroid gland in
the neck. Occasionally, a person is born with one or more of the parathyroid
glands embedded in the thyroid, in the thymus, or located elsewhere around this
area. In most such cases, however, the glands function normally.
Though their names are similar, the thyroid and parathyroid glands are
entirely different glands, each producing distinct hormones with specific
functions. The parathyroid glands secrete PTH, a substance that helps maintain
the correct balance of calcium and phosphorus in the body. PTH regulates the
level of calcium in the blood, release of calcium from bone, absorption of
calcium in the intestine, and excretion of calcium in the urine.
When the level of calcium in the blood falls too low, the parathyroid glands
secrete just enough PTH to restore the blood calcium level.
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What is hyperparathyroidism?
If the parathyroid glands secrete too much hormone, as happens in primary
hyperparathyroidism, the balance is disrupted: Blood calcium rises. This
condition of excessive calcium in the blood, called hypercalcemia, is what
usually signals the doctor that something may be wrong with the parathyroid
glands. In 85 percent of people with primary hyperparathyroidism, a benign tumor
called an adenoma has formed on one of the parathyroid glands, causing it to
become overactive. Benign tumors are noncancerous. In most other cases, the
excess hormone comes from two or more enlarged parathyroid glands, a condition
called hyperplasia. Very rarely, hyperparathyroidism is caused by cancer of a
parathyroid gland.
This excess PTH triggers the release of too much calcium into the
bloodstream. The bones may lose calcium, and too much calcium may be absorbed
from food. The levels of calcium may increase in the urine, causing kidney
stones. PTH also lowers blood phosphorus levels by increasing excretion of
phosphorus in the urine.
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Why are calcium and phosphorus so important?
Calcium is essential for good health. It plays an important role in bone and
tooth development and in maintaining bone strength. Calcium is also important in
nerve transmission and muscle contraction.
phosphorus is found in all bodily tissue. It is a main part of every cell
with many roles in each. Combined with calcium, phosphorus gives strength and
rigidity to your bones and teeth.
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What causes hyperparathyroidism?
In most cases doctors don't know the cause. The vast majority of cases occur
in people with no family history of the disorder. Only about 5 percent of cases
can be linked to an inherited problem. Familial multiple endocrine neoplasia
type 1 is a rare, inherited syndrome that affects the parathyroids as well as
the pancreas and the pituitary gland. Another rare genetic disorder, familial
hypocalciuric hypercalcemia, is sometimes confused with typical
hyperparathyroidism. Each accounts for about 2 percent of primary
hyperparathyroidism cases.
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How common is hyperparathyroidism?
In the United States, about 100,000 people develop the disorder each year.
Women outnumber men two to one, and risk increases with age. In women 60 years
and older, two out of 1,000 will develop hyperparathyroidism each year.
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What are the symptoms of hyperparathyroidism?
A person with hyperparathyroidism may have severe symptoms, subtle ones, or
none at all. Increasingly, routine blood tests that screen for a wide range of
conditions, including high calcium levels, are alerting doctors to people who
have mild forms of the disorder even though they are symptom-free.
When symptoms do appear, they are often mild and nonspecific, such as a
feeling of weakness and fatigue, depression, or aches and pains. With more
severe disease, a person may have a loss of appetite, nausea, vomiting,
constipation, confusion or impaired thinking and memory, and increased thirst
and urination. Patients may have thinning of the bones without symptoms, but
with risk of fractures. Increased calcium and phosphorus excretion in the urine
may cause kidney stones.
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How is hyperparathyroidism diagnosed?
Hyperparathyroidism is diagnosed when tests show that blood levels of calcium
and parathyroid hormone are too high. Other diseases can cause high blood
calcium levels, but only in hyperparathyroidism is the elevated calcium the
result of too much parathyroid hormone. A blood test that accurately measures
the amount of parathyroid hormone has simplified the diagnosis of
hyperparathyroidism.
Once the diagnosis is established, other tests may be done to assess
complications. Because high PTH levels can cause bones to weaken from calcium
loss, a measurement of bone density can help assess bone loss and the risk of
fractures. Abdominal images may reveal the presence of kidney stones and a
24-hour urine collection may provide information on kidney damage, the risk of
stone formation, and the risk of familial hypocalciuric hypercalcemia.
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How is hyperparathyroidism treated?
Surgery to remove the enlarged gland (or glands) is the main treatment for
the disorder and cures it in 95 percent of operations.
Calcimimetics are a new class of drug that turns off secretion of PTH. They
have been approved by the Food and Drug Administration for the treatment of
hyperparathyroidism secondary to kidney failure with dialysis, and primary
hyperparathyroidism caused by parathyroid cancer. They have not been approved
for primary hyperparathyroidism, but some physicians have begun prescribing
calcimimetics for some patients with this condition. Patients can discuss this
class of drug in more detail with their physicians.
Some patients who have mild disease may not need immediate treatment,
according to panels convened by the National Institutes of Health (NIH) in 2002.
Patients who are symptom-free, whose blood calcium is only slightly elevated,
and whose kidneys and bones are normal may wish to talk with their physicians
about long-term monitoring. In the 2002 recommendation, periodic monitoring
would consist of clinical evaluation, measurement of serum calcium levels, and
bone mass measurement. If the patient and physician choose long-term follow-up,
the patient should try to drink lots of water, get plenty of exercise, and avoid
certain diuretics, such as the thiazides. Immobilization (inability to move) and
gastrointestinal illness with vomiting or diarrhea can cause calcium levels to
rise. Patients with hyperparathyroidism should seek medical attention if they
find themselves immobilized, vomiting, or having diarrhea.
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Are there any complications associated with parathyroid surgery?
Surgery for hyperparathyroidism is highly successful with a low complication
rate when performed by surgeons experienced with this condition. About 1 percent
of patients undergoing surgery experience damage to the nerves controlling the
vocal cords, which can affect speech. One to 5 percent of patients lose all
their parathyroid tissue and thus develop chronic low calcium levels, which may
require treatment with calcium or vitamin D. The complication rate is slightly
higher for hyperplasia than it is for adenoma since more extensive surgery is
needed.
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Are parathyroid imaging tests needed before surgery?
The NIH panels recommended against the use of expensive imaging tests to
locate benign tumors before initial surgery. Such tests are not likely to
improve the success rate of surgery, which is about 95 percent when performed by
experienced surgeons. Simple imaging tests before surgery are preferred by some
surgeons. Localization tests are useful in patients having a second operation
for recurrent or persistent hyperparathyroidism.
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Which doctors specialize in treating hyperparathyroidism?
Endocrinologists are doctors who specialize in hormonal problems.
Nephrologists are doctors who specialize in kidney and mineral disorders. Along
with surgeons who are experienced in endocrine surgery, endocrinologists and
nephrologists are best qualified to treat people with hyperparathyroidism.
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For More Information
American Association of Clinical Endocrinologists
245 Riverside Ave.
Suite 200
Jacksonville, FL 32202
Phone: <?XML:NAMESPACE PREFIX = SKYPE />
904–353–7878
Fax: 904–353–8185
Internet: www.aace.com
American Association of Endocrine Surgeons
Dr. Janice L. Pasieka
Room 1014 North Tower
Foothills Medical Centre
1403–29 Street N.W.
Calgary, Alberta, Canada T2N 2T9
Phone:
403–944–2491
Fax: 403–283–4130
Internet: www.endocrinesurgery.org
The American Society for Bone and Mineral Research
2025 M Street, NW
Suite 800
Washington, DC 20036–3309
Phone:
202–367–1161
Fax: 202–367–2161
E-Mail: asbmr@smithbucklin.com
Internet: www.asbmr.org
The Endocrine Society
8401 Connecticut Ave.
Suite 900
Chevy Chase, MD 20815
Phone:
1–888–363–6274
or
301–941–0200
Fax: 301–941–0259
Email: endocrinenews@endo-society.org
Internet: www.endo-society.org
The Paget Foundation for Paget's Disease of Bone and Related
Disorders
120 Wall Street
Suite 1602
New York, NY 10005–4001
Phone:
212–509–5335
or
1–800–237–2438
Fax: 212–509–8492
Email: PagetFdn@aol.com
Internet: www.paget.org