Article title: Hyperparathyroidism: NIDDK
Main condition: Hyperparathyroidism
Conditions: Hyperparathyroidism, Parathyroid
Primary hyperparathyroidism is a disorder of the
parathyroid glands. Most people with this disorder have one or more
enlarged, overactive parathyroid glands that secrete too much parathyroid
hormone. In secondary hyperparathyroidism, a problem such as kidney
failure makes the body resistant to the action of parathyroid hormone.
This e-pub focuses on primary hyperparathyroidism.
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, the thymus, or
elsewhere in the chest. In most such cases, however, the glands function
Though their names are similar, the thyroid and parathyroid glands are
entirely separate glands, each producing distinct hormones with specific
functions. The parathyroid glands secrete parathyroid hormone (PTH), a
substance that helps maintain the correct balance of calcium and
phosphorous in the body. PTH regulates release of the calcium from bone,
absorption of calcium in the intestine, and excretion of calcium in the
When the amount of calcium in the blood falls too low, the parathyroid
glands secrete just enough PTH to restore the balance.
What Is Hyperpara-
If the glands secrete too much hormone, as in
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
In 85 percent of people with this disorder, a benign
tumor (adenoma) has formed on one of the parathyroid glands, causing it to
become overactive. 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 acts to lower blood phosphorous levels by
increasing excretion of phosphorus in the urine.
Why Are Calcium and Phosphorous So Important?
Calcium is essential for good health. It plays
an important role in bone and tooth development and in maintaining bone
strength. It is also important in nerve transmission and muscle
contraction. Phosphorous is found in every body tissue. Combined with
calcium, it gives strength and rigidity to your bones and teeth.
What Causes Hyperpara-
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 3 to 5 percent of cases can be linked to an inherited
Familial endocrine neoplasia type I is one 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.
How Common Is Hyperpara-
In the U.S., about 100,000 people develop the
disorder each year.
Women outnumber men by 2 to 1, and risk increases with
age. In women 60 years and older, 2 out of 1,000 will get
What Are the Symptoms of Hyperpara-
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, though symptom-free, have mild
forms of the disorder.
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 phosphorous
excretion in the urine may cause kidney stones. Patients with
hyperparathyroidism may be more likely to develop peptic ulcers, high
blood pressure, and pancreatitis.
How Is Hyperpara-
Hyperparathyroidism is diagnosed when tests show
that blood levels of calcium as well as 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 may be done to assess bone
loss and the risk of fractures. Abdominal radiographs may reveal the
presence of kidney stones and a 24-hour urine collection may provide
information on kidney damage and the risk of stone formation.
How Is Hyperpara-
Surgery to remove the enlarged gland (or glands)
is the only treatment for the disorder and cures it in 95 percent of
cases. However, some patients who have mild disease may not need immediate
treatment, according to a panel of experts convened by the National
Institutes of Health in 1990. Patients who are symptom-free, whose blood
calcium is only slightly elevated, and whose kidneys and bones are normal,
may wish to talk to their doctor about long-term monitoring. In the
panel's recommendation, monitoring would consist of clinical evaluation
and measurement of calcium levels and kidney function every 6 months,
annual abdominal x-ray, and bone mass measurement after 1 to 2 years. If
the disease shows no signs of worsening after 1 to 3 years, the interval
between exams may be lengthened. If the patient and doctor choose
long-term followup, the patient should try to drink lots of water, get
plenty of exercise, and avoid certain diuretics, such as the thiazides.
Immobilization and gastrointestinal illness with vomiting or diarrhea can
cause calcium levels to rise, and if these conditions develop, patients
with hyperparathyroidism should seek medical attention.
Are There Any Complications Associated With Parathyroid
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 have damage to the nerves controlling the vocal cords, which can
affect speech. One to five percent of patients develop chronic low calcium
levels, which may require treatment with calcium and/or vitamin D. The
complication rate is slightly higher for hyperplasia than it is for
adenoma since more extensive surgery is needed.
Are Parathyroid Imaging Tests Needed Before Surgery?
The National Institutes of Health panel
recommended against the use of expensive imaging tests to locate benign
tumors before initial surgery. Research shows that such tests do not
improve the success rate of surgery, which is about 95 percent when
performed by experienced surgeons. Localization tests are useful in
patients having a second operation for recurrent or persistent
Which Doctors Specialize In Treating
Endocrinologists (doctors who specialize in
hormonal problems), nephrologists (doctors who specialize in kidney and
mineral disorders), and surgeons who are experienced in endocrine surgery.
A listing of medical specialists and members of the American Association
of Endocrine Surgeons, the American Society of Clinical Endocrinologists,
and the American Society of Bone and Mineral Research is available at a
The Paget Foundation for Paget's Disease of Bone
and Related Disorders
120 Wall Street, Suite 1602
New York, NY
800-23-PAGET or (212) 509-5335
Bilezikian, John P. et al. The
Parathyroids: Basic and Clinical Concepts.
New York: Raven Press,
Parisien, May, et al. "Bone Disease in Primary Hyperparathyroidism,"
Endocrinology and Metabolism Clinics of North America. Vol.
19, No. 1, March, 1990.
Potts, John T., Jr. "Management of Asymptomatic Hyperparathyroidism,"
Journal of Endocrinology and Metabolism Vol. 70, No. 6, 1990.
National Institutes of Health. "Diagnosis and Management of
Asymptomatic Primary Hyperparathyroidism: Consensus Development Conference
Statement," Annals of Internal Medicine Vol. 114, No. 7,
April 1, 1991. 593-596. Reprints are also available from the Office of
Medical Applications of Research (OMAR) Consensus Program Clearinghouse,
P.O. Box 2577, Kensington, MD 20891 1-800-NIH-OMAR.
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NIH Publication No. 95-3425
e-text posted: 12 February 1998