Normal
Parathyroid Gland Function.
How Parathyroid Glands Work.
Parathyroid glands control
the calcium in our blood and bones. Learn how
parathyroid glands work by making parathyroid hormone to control
blood and bone calcium. This page of Parathyroid.com discusses the
normal function of parathyroid glands, how parathyroid glands
monitor and control blood calcium and what it means to have high
blood calcium. Spanish
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The
sole purpose of the parathyroid glands is to control calcium within the
blood in a very tight range between 9.0 and 10.1 . In doing so,
parathyroids also control how much calcium is in the bones, and therefore, how strong and dense the bones are. Although the parathyroid
glands are located next to (and sometimes inside) the thyroid gland, they have
no related function. The thyroid gland regulates the body’s metabolism
and has no effect on calcium levels while parathyroid glands regulate calcium
levels and have no effect on metabolism. Calcium is the element
that allows the normal conduction of electrical currents along nerves--its
how our nervous system works and how one nerve 'talks' to the next. Our
entire brain works by fluxes of calcium into and out of the nerve cells. Calcium is
also the primary element
which causes muscles to contract. (editor's note, almost all of us adults
live with calcium levels in the mid 9 range; there are almost no adults
who feel well with calcium levels below 9 or above 10.2).
Knowing these
two major functions of calcium helps explain why people can get a tingling
sensation in their fingers or cramps in the muscles of their hands when
calcium levels drop
below normal. A sudden drop in the calcium level (like after a
successful parathyroid operation where the patient doesn't take their
calcium pills for the first few days after the surgery) can cause patients
to feel "foggy", "weird" or "confused like my
brain isn't working correctly". The brain DEMANDS a normal
steady-state calcium level, so any change in the amount of calcium can
cause the brain to feel un-loved and the patient to feel bad. Likewise, too much parathyroid hormone causes too high a calcium level--and
this can make a person feel run down, cause them to sleep poorly, make them more irritable
than usual, and even cause a decrease in memory. In fact, the most common
symptoms for patients with parathyroid disease are related to the brain,
and include depression and lack of energy! After
removal of a bad parathyroid gland, most people will feel dramatically
better. Some say its like "someone turned the lights on". Most people
don't feel good when their calcium level is above 10, and the vast
majority of people will feel pretty darn tired and run-down when their
calcium level is above 10.5. Go to the page on Symptoms
of Hyperparathyroidism to lean more about symptoms of high calcium.
Normal Parathyroid Activity /
Normal Parathyroid Function.
Although
the four parathyroid glands are quite small, they have a very rich blood supply. This
suits them well since they are required to monitor the calcium level in
the blood 24 hours a day. As the blood filters through the parathyroid glands, they detect the amount of calcium present in the blood and react
by making more or less parathyroid hormone (PTH). When the calcium level
in the blood is too low, the cells of the parathyroids sense it and make
more parathyroid hormone. Once the parathyroid hormone is released into the
blood, it circulates to act in a number of places to increase the amount
of calcium in the blood (like removing calcium from bones). When the calcium level in the blood is too high,
the cells of the parathyroids make less parathyroid hormone (or stop making it altogether),
thereby
allowing calcium levels to decrease. This feed-back mechanism runs constantly, thereby maintaining calcium (and parathyroid hormone) in a very narrow "normal" range.
In a normal person with normal parathyroid glands, their parathyroid glands will
turn on and off dozens of times per day...in an attempt to keep the calcium
level in the normal range so our brain and muscles function properly. Those of
us with normal parathyroid function will have calcium levels that are
constant... with almost zero variability. For instance, if your calcium level is
9.6 this week and you have normal parathyroid glands, your calcium will be
between 9.4 and 9.8 every time you measure it for most of your life.
Contrast this with somebody that has a bad parathyroid gland. The bad
parathyroid gland has lost it's regulatory system and these patients have
calcium levels that bounce around from high to low, never the same number twice:
up - down, up - down, up, up, down, up, up, down. The control system is lost in
parathyroid tumors. This is hyperparathyroidism.
How Does Parathyroid Hormone
Increase Blood Calcium?
Like
all endocrine glands, parathyroids make a hormone (a small protein capable
of causing distant cells in the body to react in a specific manner). Parathyroid
hormone (PTH) has a very powerful influence on the cells of the bones which
causes them to release their calcium into the bloodstream. Calcium is the
main structural component of bones which give them their rigidity--but remember
from our first page, the principle purpose
of the bones is to provide a storage system for calcium--so our brain will
never be without calcium. Under
the presence of parathyroid hormone, bones will give up their calcium in
an attempt to increase the blood level of calcium. Under normal conditions,
this process is very highly tuned and the amount of calcium in our bones
remains at a normal high level. Under the presence of too much parathyroid
hormone, however, the bones will continue to release their calcium into
the blood at a rate which is too high resulting in bones which have too
little calcium. This condition is called osteopenia
and osteoporosis and is illustrated in this video where the bone develops
more "pores" (or holes) and less bone mass. When bones are exposed to high levels of parathyroid
hormone for several years they become brittle and much more prone to fractures.
Another way in which the parathyroid hormone acts to increase blood levels of
calcium is through its influence on the intestines. Under the presence
of parathyroid hormone the lining of the intestine becomes more efficient
at absorbing calcium normally found in our diet.
Parathyroid Function Quick
Facts
The parathyroid glands monitor the calcium in the blood 24
hours per day.
The four parathyroid glands make more or
less parathyroid
hormone (PTH) in response to the level of calcium in the
blood.
When the calcium in our blood goes too low,
the parathyroid glands make more PTH.
Increased PTH causes the body to put more calcium into the
blood.
Increased PTH causes the bones to release their calcium into
the blood.
When the calcium in our blood goes too high,
normal parathyroid glands STOP making PTH--they shut down.
Calcium is the most important element for
the nervous system, the muscular system, and the skeletal
system.
Calcium provides the electrical system for our nerves,
and muscles, allowing the nerves to conduct electricity
and the muscles to contract.
This is why parathyroid disease (over-production of
PTH from a parathyroid tumor leading to high blood
calcium)
causes symptoms of the brain, muscles, and bones.
People with normal parathyroid glands
have calcium levels that jump around very little or never...
it's almost always the same number in the 9's.
People with a bad parathyroid gland
(hyperparathyroidism) have grown a tumor in one of their
parathyroid glands that has lost it's regulatory system... so
the calcium levels jump around all over the place, usually being
high (over 10.2).
It is never normal to have high calcium
levels.
Adults over the age of 30 should have almost
every calcium level be 10.1 or lower.
Adults over the age of 40 who have
persistent calcium levels above 10.1 almost certainly have a
parathyroid tumor.
High calcium levels almost 100% of the time
means you have a tumor on one of your parathyroid glands.
These are not cancerous tumors--instead they cause trouble
by making too much hormone.
People don't like having high calcium... it
makes them feel bad; ruins their kidneys, liver and arteries;
causes strokes and cardiac rhythm problems; causes kidney
stones and osteoporosis; and can even increase the risk of
cancers such as breast cancer.
If you have hyperparathyroidism (a bad
parathyroid gland), you should get it removed. You will live
longer and feel better. Humans don't like high calcium!
If your lab tests say that having calcium
levels up to 10.4 or even 10.6 are normal, then that lab is
including children and teenagers into their normal range.
It is normal for children and teenagers
to have blood calcium levels up to 10.4 or even 10.5 on
occasion. (They are still building bones!).
It is normal for young adults in their
twenties to have calcium levels up to 10.3 or 10.4.
Once you are over 40, it is OK to have
an occasional calcium level up to 10.2 (not above).
If you are over 40, then it is not
normal to have frequent or persistent calcium levels above
10.1. If your doctor says that it is OK for you because
the lab values say this is OK, then you tell them
"Not True". That normal range includes
kids and that is not the normal range for adults
over 40.
If you are over 40 and have persistent
calcium levels above 10.1, then you need to ask about
being tested for hyperparathyroidism.
Parathyroid.com
is an educational service of the Norman Parathyroid Center,
the world's leading
parathyroid treatment center performing about 2600
parathyroid operations annually.
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May
2013
The
sole purpose of the parathyroid glands is to control calcium within the
blood in a very tight range between 9.0 and 10.1 . In doing so,
parathyroids also control how much calcium is in the bones, and therefore, how strong and dense the bones are. Although the parathyroid
glands are located next to (and sometimes inside) the thyroid gland, they have
no related function. The 
