Side Effects of thyroid hormone products
http://thyroid.about.com/cs/thyroiddrugs/a/overview.htm
Thyroid Hormone Replacement Drugs
When your thyroid is either underactive, non-functioning, or has
been all or in part surgically removed, you are considered
hypothyroid.
The conventional
treatment for hypothyroidism is thyroid hormone replacement --
basically, taking a prescription a drug that acts similarly in
the body to the human hormone thyroxine that the thyroid would
normally produce.
Levothyroxine/Synthetic T4
The vast majority of doctors prescribe the synthetic drug known
as levothyroxine for thyroid hormone replacement. The most
commonly known brand of levothyroxine is Synthroid. There's also
Levoxyl, Levothroid, Unithroid, and many brands outside the
U.S.
In addition, there are "generic" versions of the T4 drugs, but
many doctors do not recommend them. Studies have shown the brand
name levothyroxine drugs in the
U.S.
to be bioqeuivalent, meaning that they accomplish the same thing
from a medical standpoint Different brands, however, have
different fillers, and a small number of patients apparently are
allergic to the fillers in one versus another. Levothyroxine
provides a synthetic version of one hormone, thyroxine, known as
T4. Some people with hypothyroidism find that levothyroxine
therapy is sufficient treatment for their hypothyroidism.
Liothyronine/Synthetic T3
Some doctors treat hypothyroidism using levothyroxine, plus an
additional drug, liothyronine (brand name, Cytomel), or
prescribe it in a time released compounded version. Liothyronine
is a synthetic version of triiodothyronine, abbreviated as T3,
the active thyroid hormone in the body. In a person with normal
health and thyroid function, the thyroid produces mainly T4 and
some T3, and the T4 is converted to T3, which is then the active
hormone used by the body's cells. Some doctors and
endocrinologists use supplemental T3. This was supported in
research featured in the
New England Journal of Medicine,
but
some researchers in 2003
have also claimed it to be ineffective. There is still a belief
by some practitioners that patients do not need T3, because they
will convert T4 into the T3 the body needs. The alternative
medical community believes that impaired conversion of T4 to T3
may create a deficiency in T3 that warrants direct T3
supplementation.
Liotrix / Synthetic T4/T3 Combination
The synthetic T4/T3 combination drug is liotrix, brand name
Thyrolar. This drug is not very regularly prescribed, but is
preferred by some physicians who wish to provide both T4 and T3,
but prefer a synthetic drug.
Natural Thyroid
Natural thyroid is dessicated thyroid, derived from the gland of
pigs. It was the standard thyroid drug until levothyroxine came
on the market in the second half of the 20th century. Some
doctors, more often osteopaths, naturopaths, and holistics
M.D.s,
are in favor of these natural drugs,
because they believe that since the drug contains a full
spectrum of thyroid hormones, beyond just the T4 and T3, it most
closely mimics the human thyroid hormone. The most popular brand
of natural thyroid is Armour thyroid.
Levothyroxine Side Effects
Possible Levothyroxine Side Effects
As with any
medication, levothyroxine can cause allergic reactions. Seek
medical attention immediately if you develop any signs of an
allergic reaction, including:
·
Wheezing or difficulty breathing
·
An
unexplained rash
·
Hives
·
Itching
·
Unexplained swelling (especially of the lips, mouth, or throat).
Levothyroxine
side effects typically occur when the dosage is too high. Too
much levothyroxine can cause symptoms of hyperthyroidism (an
excess of thyroid hormones). Because hyperthyroidism can be
quite dangerous, any of these symptoms should be reported to
your healthcare provider, as they may signal that your
levothyroxine dosage needs to be decreased. These
side effects may include:
·
Feeling hot all the time and increased sweating
·
Fever
·
An
increased appetite, along with weight loss
·
Heart
palpitations
·
A
rapid heart rate (tachycardia)
·
Heart failure, chest pain, or a
heart attack
·
Difficult or painful breathing
·
Insomnia (see
Levothyroxine and Insomnia)
·
Emotional changes
·
Hair
loss (see
Levothyroxine and Hair Loss)
·
Flushing
·
Broken
bones or other signs of weakened bones
·
Menstrual problems or fertility problems
·
Shakiness (tremors) or muscle weakness
·
Hyperactivity, nervousness,
anxiety, or irritability
·
High blood pressure (hypertension)
·
Diarrhea, vomiting, or abdominal cramps (stomach
cramps)
·
Seizures.
You should
report any levothyroxine side effect to your healthcare provider
right away, as it may be a symptom of hyperthyroidism and an
indication that your levothyroxine dosage is too high. Also,
seek immediate medical attention if you notice any signs of an
allergic reaction while taking levothyroxine.
http://endocrine-system.emedtv.com/levothyroxine/levothyroxine-side-effects.html
Comments from
Dr. Martin Wang:
(1). It is so
common that once patient complain chronic fatigue, and if the
blood level of T4 is low, doctors are so ready to give
levothyroxine to patient, with the hope to increase the physical
energy for the patients. Doctors seem never search other reasons
that may contribute to the tiredness feeling of the patients.
They do not care if the application of artificial thyroid
hormone-similar products for a long time will have what kind of
disadvantage to the patients.
Similar to any
hormones in the body, such as insulin, estrogen and others, one
of the reverse feedback regulation for the production of the
hormone by the corresponding hormone producing glands is their
products. This means, if you have more insulin in the blood, the
insulin will prevent more production of insulin by the pancreas.
Similarly, if you have more thyroid hormone in the blood, it
will pass signal to the thyroid gland and makes the gland to
produce less thyroid hormone to release into the blood.
So, if we
increase the thyroid hormone level by application of
levothyroxine, the thyroid gland may “feel” that there is enough
thyroid hormone in the blood so do not work hard to produce more
thyroid hormone. After a long time, it’s hormone producing cells
may “shrink” and lose its ability to produce more thyroid
hormone. This is why it could be difficult to quit the
levothyroxine when it has been used for a long time.
(2). It is hard
in clinic for western medical doctor to identify the exact
reasons that contribute to the tiredness feelings of patients
and the reasons that cause the lower blood level of thyroid
hormone. I know it is difficult but doctors should be care for
the prescription of levothyroxine. Prescribe it when it is
definitely needed. For example, if the whole thyroid glands have
been removed by surgery for the treatment of thyroid cancer.
Whenever there is even a part of the thyroid cells in the
glands, try not to disturb it. Doctor should try to solve the
chronic fatigue by other means.
(3). To us, to
use the levothyroxine for the treatment of chronic fatigue is as
to use gun to shoot mosquito. It does not touch the point and
waste the medicine.
The application
of the Traditional Chinese Medicine is a very promising means to
solve the chronic fatigue. In my experience, it is as easy as to
solve depression and anxiety in patients. It is usually only
needed for several weeks (usually within one week), the chronic
fatigue and emotional disorders can be much improved. So, always
try the no harm therapy before starting something that may need
you to take for years even for ever.
Regulation of
Thyroid Hormones
The thyroid gland concentrates
iodine that the body absorbs from various foods to make thyroid
hormones. The thyroid gland makes mostly T4. Very
little T3 is made by the thyroid gland. The liver and
other organs convert T4 into T3. Certain
diseases and drugs can affect the conversion of T4
into T3.
Both T4 and T3
circulate in the blood, mostly bound to certain proteins.
Thyroid hormones become active in their role of controlling the
speed of vital body functions when they are freed from protein
binding. The body regulates a balance between bound thyroid
hormones and free thyroid hormones.
Through a complex interaction
between the hypothalamus (a part of the brain) and the pituitary
gland (located inside the skull, just underneath the brain), the
thyroid gland knows how much of its hormones to produce. The
hypothalamus makes thyrotropin-releasing hormone, which then
stimulates the pituitary gland. The pituitary gland responds by
making another hormone called thyroid-stimulating hormone, or
TSH. As the name suggests, thyroid-stimulating hormone
stimulates the thyroid gland to make hormones. If the level of
thyroid hormones in the blood climbs above what is needed, the
pituitary gland makes less thyroid-stimulating hormone. The
thyroid gland then cuts back on making thyroid hormones. If the
level of thyroid hormones in the blood falls too low, the
pituitary gland makes more thyroid-stimulating hormone. In
response, the thyroid gland makes and secretes more thyroid
hormones. The body adjusts the amount of thyroid hormones to
suit its needs in the same way a thermostat adjusts the
temperature in a house.
Thyroid Problems Overview
The
thyroid gland is located
on the front part of the neck below the
thyroid cartilage (Adam's
apple). The gland produces
thyroid hormones, which
regulate body
metabolism. Thyroid
hormones are important in regulating body energy, the body's use
of other hormones and
vitamins, and the growth
and maturation of body tissues.
Diseases of the
thyroid gland can result in either production of too much (hyperthyroidism)
or too little (hypothyroidism)
hormone.
Production of thyroid hormones: The process of hormone synthesis
begins in a part of the brain called the
hypothalamus. The
hypothalamus releases thyrotropin-releasing hormone (TRH). The
TRH travels through the bloodstream to the
pituitary gland, also in
the brain. In response, the pituitary gland then releases
thyroid-stimulating hormone (TSH)
into the blood. The TSH then stimulates the thyroid to produce
the two main thyroid hormones, L-thyroxine (T4) and
triiodothyronine (T3). The
thyroid gland also needs adequate amounts of dietary
iodine to be able to
produce T4 and T3.
Regulation of
thyroid hormone
production: To prevent the overproduction or underproduction of
thyroid hormones, the pituitary gland can sense how much hormone
is in the blood and adjust the production of hormones
accordingly. For example, when there is too much thyroid hormone
in the blood, the TRH does not work effectively to stimulate the
pituitary gland. In addition, too much thyroid hormone will
prevent the release of TSH from the pituitary gland. The sum
effect of this is to decrease the amount of TSH released from
the pituitary gland, resulting in less production of thyroid
hormones in the thyroid gland. This then works to restore the
amount of thyroid hormone in the blood to normal. Defects in
these regulatory pathways may result in hypothyroidism or
hyperthyroidism.
http://www.emedicinehealth.com/thyroid_problems/article_em.htm
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