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Hyperparathyroidism
You have four tiny
parathyroid glands, one located on each of the
four corners of another gland — the thyroid,
which is located at the base of your neck. But
in spite of the similarity in name and location,
the parathyroid glands and thyroid gland are
separate glands with separate functions.
Your thyroid gland,
for example, helps regulate nearly every aspect
of your metabolism, from how quickly your heart
beats to the rate at which you burn calories.
The parathyroids, on the other hand, produce a
hormone that helps maintain the proper balance
of calcium and phosphorus in your body. When the
glands sense that blood calcium levels are
either too low or too high, they secrete just
enough parathyroid hormone (PTH) to restore the
levels to normal. Sometimes, however, the glands
produce too much PTH — a condition known as
hyperparathyroidism. This leads to consistently
high levels of calcium in your blood (hypercalcemia).
Each year,
approximately 100,000 Americans develop what's
known as primary hyperparathyroidism, when one
or more parathyroid glands become overactive.
Secondary hyperparathyroidism is less common. It
occurs when another medical condition —
particularly kidney failure — causes your
parathyroid glands to secrete too much PTH.
Left untreated,
hyperparathyroidism can cause additional health
problems, such as kidney damage and a loss of
calcium from your bones, leading to
osteoporosis.
If you have mild
hyperparathyroidism, you may not need any
treatment, although your blood-calcium levels,
kidney function and bone health will need to be
regularly checked. When your kidneys or bones
are affected, or you have bothersome symptoms,
surgery may be the best option.
Signs
and symptoms
More than half the
people with hyperparathyroidism have no
symptoms. In those who do, the symptoms
frequently come on slowly and are usually
subtle, such as a feeling of weakness or
fatigue, or vague aches and pains. But more
severe signs and symptoms can develop over time,
including:
- Increased
thirst and urination due to increased
excretion of calcium in the urine (hypercalciuria)
- Kidney stones
- Heartburn or
abdominal pain from peptic ulcer disease or
pancreatitis
- Nausea,
vomiting or loss of appetite
- Thinning bones,
leading to an increased risk of fractures
- Confusion or
poor memory
- Muscle weakness
or fatigue
Causes
Calcium is
the most abundant mineral in your body. It's
essential for the development and health of your
teeth and bones. Calcium also helps your blood
clot, aids in the transmission of signals in
nerve cells and plays a role in muscle
contraction. Another mineral, phosphorus, works
in conjunction with calcium in these areas.
The parathyroid
glands maintain proper levels of both calcium
and phosphorus in your body by turning the
secretion of parathyroid hormone (PTH) off or
on, much as a thermostat controls a heating
system to maintain a constant air temperature.
Vitamin D also is involved in regulating the
amount of calcium in your blood.
Normally, this
balancing act works well. When calcium levels in
your blood fall too low, your parathyroid glands
secrete the right amount of PTH to restore the
balance. PTH raises calcium levels by releasing
calcium from your bones and increasing the
amount of calcium absorbed from your small
intestine. When blood-calcium levels are too
high, the parathyroids produce less PTH. But
sometimes one or more parathyroid glands produce
too much hormone, leading to abnormally high
levels of calcium and low levels of phosphorus
in your blood.
In more than 80
percent of people with hyperparathyroidism, the
cause is a benign growth (adenoma) on one of the
parathyroid glands. Most other cases result from
excess hormone that's produced when two or more
parathyroids become enlarged — a condition known
as hyperplasia.
Secondary
hyperparathyroidism occurs when another medical
condition, such as kidney failure, causes your
parathyroid to produce too much PTH. Infants and
children who have rickets — a disease caused by
severe vitamin D deficiency — also may develop
secondary hyperparathyroidism. In rare cases,
hyperparathyroidism may be caused by cancer of
one of the parathyroid glands.
Risk
factors
Twice as many women
as men develop primary hyperparathyroidism, and
risk increases with age. Two out of every 1,000
women age 60 and older will develop the disease.
Infants or adults
with vitamin D deficiency also are at greater
risk of developing secondary
hyperparathyroidism. Most children and adults
get sufficient amounts of vitamin D from food —
especially eggs, fish, green vegetables and
fortified milk products — and from exposure to
sunlight, which changes a chemical in the skin
into an active form of vitamin D. But several
factors have caused a resurgence of vitamin D
deficiency among some infants and children.
Chief among these
are breast-feeding and the use of sunscreen.
Although breast milk is a baby's ideal food, it
doesn't contain vitamin D. If your baby is
breast-fed only, talk to your pediatrician about
a vitamin D supplement. In addition, children
who live in northern or cloudy climates or who
consistently use sunscreen may not receive
enough sunlight to manufacture vitamin D in
their skin.
Also at increased
risk are people with familial endocrine
neoplasia type I — a rare inherited syndrome
that affects the parathyroids as well as the
pancreas and pituitary gland. Having familial
hyperparathyroidism — hyperparathyroidism that
runs in families — also puts you at risk.
Screening and diagnosis
You may not realize
you have hyperparathyroidism because early
symptoms tend to be vague or nonexistent. When
symptoms do develop, they frequently resemble
those of other conditions. That's why doctors
rely on blood tests to diagnose
hyperparathyroidism.
Your doctor may be
alerted to the disease when high levels of
calcium show up on routine blood tests, or on
tests that screen for a number of conditions.
But because other diseases and certain
medications also can increase the amount of
calcium in your blood, you'll receive a
diagnosis of hyperparathyroidism only if
blood tests show high levels of both calcium and
parathyroid hormone.
Once
hyperparathyroidism is diagnosed, your doctor
may recommend tests to check for complications.
These may include bone density tests to assess
bone loss, and a 24-hour collection of urine to
provide information on your kidney function.
If your doctor
suspects you have kidney stones, he or she may
also suggest an abdominal X-ray or an
ultrasound, a diagnostic technique that combines
high-frequency radio waves and computer
processing to view your kidneys.
Sometimes you and
your doctor may choose not to treat
hyperparathyroidism right away, especially if
your blood calcium is only mildly elevated. If
so, your doctor will likely want to check your
calcium levels and kidney function every six
months and may also recommend an annual
abdominal X-ray and a bone density test every
one to two years. If the disease doesn't become
worse over time, you may not need to have these
tests as often.
Complications
Having too
much PTH can lead to several serious
complications, including:
- Osteoporosis.
Hyperparathyroidism poses a long-term threat
to your bones — the more PTH your
parathyroids produce, the more calcium your
bones lose. The result is weak, brittle
bones that are prone to fractures.
- Kidney damage
or kidney stones. Because your body tries to
compensate for excess calcium by excreting
more of the mineral in your urine, you're at
increased risk of kidney damage or kidney
stones — small hard masses that form in your
kidneys.
- Peptic ulcers.
High blood levels of calcium stimulate your
stomach to produce more acid, making you
more prone to develop peptic ulcers.
- High blood
pressure. High calcium levels in your blood
can raise your blood pressure.
Treatment
In general,
treatment depends on the presence of
complications or symptoms and the type of
hyperparathyroidism you have.
Primary
hyperparathyroidism
If you don't have symptoms and your kidneys and
bones are healthy, you and your doctor may
choose a wait-and-see approach. Sometimes this
may be all you need, although your kidney
function, bone health and calcium levels will
need to be monitored on a regular basis.
If your symptoms are
moderate to severe, or you have complications,
or your calcium level is more than mildly
elevated, even if you don't have symptoms your
doctor will likely recommend surgery to remove
one or more parathyroid glands
(parathyroidectomy). In cases where the problem
is an adenoma, just the one gland is removed. If
all four glands are enlarged, your surgeon will
likely remove three of them and sometimes part
of the fourth.
Traditionally, this
surgery has involved a long incision,
exploration on both sides of the neck and
general anesthesia. But a newer technique, known
as minimally invasive radioguided
parathyroidectomy may offer a safer and less
invasive approach for some people. In this
procedure, doctors use a radioisotope scan
(sestamibi scan) to help locate a tumor or
abnormal parathyroid gland before surgery.
For the scan, you're
given a very small dose of a radioactive
material that's absorbed only by the overactive
parathyroid gland — not healthy ones. During the
operation, the surgeon uses the sestamibi scan
results as a map to locate the abnormal gland.
In some cases, a probe that detects
radioactivity, much as a Geiger counter does, is
used to confirm the location.
The entire operation
can usually be performed through a 1-inch
incision in your neck. It takes less than an
hour and often requires local rather than
general anesthesia. If local anesthesia is used,
you likely can go home a few hours after
surgery.
Still, all surgery
poses some risks. About 1 percent of people
undergoing parathyroid surgery experience damage
to the nerves controlling their vocal cords.
Between 1 percent and 5 percent develop
chronically low calcium levels, requiring
treatment with calcium and vitamin D. In
addition, although it's usually very effective,
hyperparathyroid surgery won't cure the problem
in every case.
For
women who have gone through menopause and have
signs of osteoporosis but no other symptoms,
hormone replacement therapy (HRT) may be an
alternative to surgery. But taking oral estrogen
and progestin may increase your risk of breast
cancer, stroke and dementia. Work with your
doctor to evaluate the risks and benefits to
help you decide what's best for you.
Secondary hyperparathyroidism
In cases of
secondary hyperparathyroidism, the first goal is
to treat the underlying problem. For many
adults, that problem is chronic kidney failure.
Because treatments that are used to manage
kidney failure won't cure hyperparathyroidism,
you'll likely need vitamin D hormone replacement
therapies to reduce the production of PTH.
Self-care
If you and
your doctor have chosen to monitor, rather than
treat, your hyperparathyroidism, the following
suggestions can help prevent complications:
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Drink plenty of
fluids, especially water. Drinking lots
of fluids can help prevent kidney stones
from forming. |
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Exercise. This is one
of the best ways to build strong bones
and slow bone loss. Try to combine
strength training with weight-bearing
exercises. Strength training builds
muscles and bones in your arms and upper
spine. Weight-bearing exercises — such
as walking, jogging, running, stair
climbing, skipping rope, skiing and
impact-producing sports — mainly affect
the bones in your legs, hips and lower
spine. If you're new to exercise, start
out slowly and build up gradually. Aim
for at least 30 minutes of exercise on
most days. |
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Get adequate amounts
of vitamin D. Premenopausal women and
postmenopausal women who use HRT should
consume at least 400 international units
(IU) of vitamin D every day.
Postmenopausal women not using HRT
should get 800 IU of vitamin D daily.
Although baking in the sun makes you
more likely to develop skin cancer,
exposing your arms or legs to sunlight
for about 10 minutes every day can
increase vitamin D levels without
increasing your cancer risk.
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Don't smoke. Smoking
has been shown to increase bone loss as
well as to dramatically increase your
risk of a number of serious health
problems, including cancer. Talk to your
doctor about the best ways to quit.
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Be alert for
conditions that may increase your
calcium levels. Certain conditions, such
as a gastrointestinal illness with
vomiting and diarrhea, can cause your
blood-calcium levels to rise. Call your
doctor if you develop any of these
conditions. |
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