Thyroid Disease
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The thyroid is an endocrine gland in the neck that regulates a
variety of bodily processes related to energy consumption, protein synthesis, and
hormone responsiveness. It participates in these pathways by producing hormones
itself, specifically thyroxine (T4) triiodothyronine (T3), and calcitonin. The delicate
balance of these hormones ultimately defines the speed and efficiency of many of
our metabolic processes, influencing the way we feel physically, mentally, and emotionally.
Thyroid problems can sigificantly affect your life. If you feel
that your thyroid is not functioning properly, please call our patient coordinator
at 1-212-679-9667 or click on
Appointment to schedule an appointment to see one of our doctors for evaluation
and testing. The TRH Stimulation Test is a more sensitive
thyroid test to detect a low thyroid that could have been missed
by routine blood tests. This is a challenge test that evaluates how well the pituitary
and thyroid gland is functioning properly. By using the TRH stimulation test we
frequently pick up the low thyroid diagnoses missed by many doctors.
Structurally, the principal thyroid hormones T4 and T3 only differ only by one iodine
atom. (T4 contains four, while T3 contains three.) T4 is actually considered a prohormone,
a precursor to T3, which becomes approximately four times more active upon conversion.
90% of the thyroid hormone is released as T4, which can circulate and be converted
to T3 as needed by the thyroid, liver, spleen, and kidneys. T3 activates the production
of proteins involved in the breakdown of nutrients to produce energy and heat. Through
these pathways, T3 and T4 regulate metabolism, body temperature, growth, and heart
rate. The other thyroid hormone, calcitonin, contributes more specifically to the
normalization of blood calcium levels.
Release of thyroid hormones T4 and T3 is controlled by the hypothalamus, the portion
of the brain considered to be the “master regulator” of hunger, thirst, fatigue,
circadian rhythms, and many other complex processes. If a shift in one of these
physiological states is warranted, the hypothalamus releases thyrotropin-releasing
hormone (TRH), which stimulates production of thyroid-stimulating hormone (TSH)
from the pituitary gland. TSH can then communicate to the thyroid gland that more
thyroid hormones should be secreted. Beyond this, T4 and T3 levels are balanced
through a feedback loop with thyrotropes, the cells in the pituitary gland which
release TSH. In other words, if T4/T3 levels are high, TSH production will be reduced
so that additional thyroid hormones are not produced. If T4/T3 levels are low, TSH
will stimulate the production of more of these hormones to maintain a balance.
Calcitonin is released by the thyroid in response to hypercalcemia, a state of high
blood calcium. By facilitating the movement of calcium from the blood into the bones,
calcitonin reduces blood calcium to more physiologically preferable levels. Should
blood calcium become too low, levels are rebalanced by parathyroid hormone (PTH)
released by the parathyroid glands. These smaller endocrine glands in the back of
the neck are located behind the thyroid. Generally, PTH seems to have a greater
impact on calcium metabolism, as parathyroid removal seems to have a more profound
effect on blood calcium balance than thyroid removal.
Thyroid hormones are also affected by other hormones in the body, such as estrogen.
Because estrogen levels reduce the efficiency of thyroid hormones, women tend to
have higher levels of T3 and T4 than men. As a result, women tend to have larger
thyroids and are more susceptible to thyroid diseases and imbalances than men.
Thyroid disease is quite prevalent, effecting as many as 20 million
Americans, many of them undiagnosed. Because of the general nature of some of the
symptoms, mild thyroid imbalances may be particularly difficult to identify. Unless
a thyroid disorder is suspected, thyroid function tests are rarely given until the
symptoms worsen or there becomes a pronounced change in the gland itself. Unfortunately,
this leads many sufferers of thyroid problems to live with their symptoms far longer
than necessary.
Thyroid Symptoms
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Are you experiencing any of these symptoms; • Fatigue and weakness • Low basal temperature
( cold intolerance) • Dry and coarse skin • Hair loss • Cold hands and feet • Weight
gain • Insomnia • Constipation • Depression • Poor memory, forgetfulness, dementia
• Nervousness and tremors • Immune system problems • Heavy menstrual periods? Then
it is a good possibility that you have a low thyroid, or HYPO-THYROIDISM.
Hypothyroidism results from an underactive thyroid gland and frequently
results in weight gain, through slowed metabolism and water retention. Low thyroid
hormone levels may also result in thinning hair, brittle nails, pale skin, poor
muscle tone, and low heart rate. Energy levels may be quite low, frequently leading
to fatigue even in the absence of exertion. Muscle cramping, painful joints, and
sensitivity to cold can also result from hypothyroidism. Thyroid hormone T3 also
influences the levels of serotonin, a neurotransmitter that helps define mood. Thus,
insufficient T3 can also lead to depression.
Are you experiencing any of these symptoms; • Fatigue and weakness • Heat intolerance
• Dry and coarse skin, clammy skin • Hair loss • Warm hands and feet • Weight loss
• Insomnia • Depression • Poor memory, forgetfulness • Nervousness and tremors •
Immune system problems • Light menstrual periods • Frequent defecation? Then it
is a good possibility that you have an overactive thyroid, or HYPER-THYROIDISM.
An overactive thyroid gland releases too many hormones, resulting in hyperthyroidism.
Because thyroid hormones speed up the rate of metabolism, increasing energy consumption,
people with hyperthyroidism often have increased appetite, but are prone to weight
loss regardless of caloric intake. They may also feel hyperactive, intolerant to
heat, short of breath, and experience heart palpitations. Extreme thirst, increased
urination, nausea, vomiting, and diarrhea can also occur. As the body’s energy supplies
are exhausted, sufferers of hyperthyroidism may feel fatigued, weak, depressed,
and even delirious. The eyelids may also remain open slightly wider than normal,
a symptom known as “Dalrymple’s sign.”
Other symptoms of thyroid that commonly accompanies hypothyroidism is goiter, a
swelling of the thyroid gland due to excessive stimulation by thyroid-stimulating
hormone (TSH). A normally functioning thyroid gland would respond to the TSH by
producing thyroid hormones which would, in turn, stop the release of TSH. In the
case of hypothyroidism, because thyroid hormone levels are never restored, TSH stimulation
never ceases. As a result, the cells in the thyroid gland divide excessively, causing
the whole gland to increase in size and bulge from the neck. The eyes may also begin
to protrude.
There are also several types of thyroiditis, characterized by inflammation of the
thyroid. The thyroid gland may become swollen, tender, and painful to touch, and
the person may develop a fever. Sometimes, thyroiditis is also accompanied by symptoms
of hyper- or hypothyroidism.
Thyroid cancer is often detected following the development of thyroid
nodules on the gland. Statistically, thyroid nodules are quite common, found in
50% of the population according to some statistics. The vast majority of these lumps
are benign and cause no symptoms at all. Still, a medical work-up is recommended
to make sure they are not cancerous. Doctors may perform ultrasounds or biopsies
to more closely examine the nodules, in case there is a problem.
Thyroid problems can sigificantly affect your life. If you feel that your thyroid
is not functioning properly, please call our patient coordinator at 1-212-679-9667
or click on Appointment
to schedule an appointment to see one of our doctors for evaluation and testing.
Causes of Thyroid Disease
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The most common cause of hyperthyroidism is Graves’ disease, an autoimmune disorder.
In patients with this disease, the immune system develops antibodies to the thyrotropin
receptors on the thyroid gland. Under normal conditions, these receptors bind thyroid-stimulating
hormone (TSH) produced by the pituitary gland, which causes the thyroid to produce
thyroid hormones. TSH is released in a controlled fashion from the pituitary gland,
meaning controlled stimulation of thyroid hormone production. In Graves’ disease
patients, the antibody binds and continuously stimulates the thyrotropin receptors,
resulting in constant release of thyroid hormones. The cause of Graves’ disease
is unknown, though it appears to have a strong hereditary component.
Historically, insufficient iodine intake was the primary cause of hypothyroidism,
and it remains a common cause in developing countries. Iodine is a major component
of thyroid hormones T3 and T4, so without it, these major thyroid hormones cannot
be made. The most common cause of hypothyroidism in individuals that have adequate
iodine levels is Hashimoto’s thyroiditis, an autoimmune disorder in which the body
mounts an immune response to the cells of the thyroid gland. As its cells are destroyed,
the thyroid becomes progressively less functional, causing T3 and T4 levels to drop
far below normal. A few specific genes involved in the regulation and specificity
of the immune response have been implicated in increasing the risk of Hashimoto’s
thyroiditis.
Other types of thyroiditis contribute to thyroid hormone imbalances, as well. Viral
infections can cause inflammation of the thyroid, leading to increased release of
thyroid hormones. Approximately 5% of pregnant women develop postpartum thyroiditis,
a condition thought to stem from changes in the immune system that occur to accommodate
pregnancy. Postpartum thyroiditis may cause hyper- or hypothyroidism (or both) as
the woman’s body rebalances itself. Most women return to normal thyroid output during
the year following the pregnancy, however, some may retain the imbalance and require
lifelong treatment for whichever condition remains.
Thyroid nodules can lead to either hyper- or hypothyroidism, depending
on whether the thyroid cells within the lump are “hot” or “cold.” “Hot” nodules
are composed of cells that release hormones in an uncontrolled way, no longer regulated
properly by the normal signals. Conversely, “cold” nodules produce no hormones,
thus contributing to hypothyroidism.
There are four different types of thyroid cancers that can potentially
cause thyroid hormone imbalances and thyroid gland enlargement. The most common
is papillary thyroid cancer, which accounts for approximate 75% of thyroid cancer
cases. Papillary tumors are cystic masses that form from otherwise normal thyroid
hormone producing tissue and tend to stay fairly localized. Follicular thyroid cancers,
however, are more invasive and more likely to spread to other parts of the body.
Medullary thyroid cancers occur in the parafollicular cells of the thyroid which
produce the hormone calcitonin. Anaplastic thyroid cancers are the rarest form of
thyroid cancer, but are the most invasive and have the poorest prognosis for patients.
Next Steps:
Thyroid problems can sigificantly affect your life. If you feel that your thyroid
is not functioning properly, please call our patient coordinator at 1-212-679-9667
to schedule an appointment to see one of our doctors for evaluation and testing.
Next Steps:
Poor health can significantly affect your life. Improve your life by changing to good health. Call our patient coordinator at 1-212-679-9667 or click on Request an Appointment to schedule an appointment with one of our doctors for evaluation and testing.
We are located at: Patients Medical PC, 800 Second Avenue, Suite 900 (Between 42nd & 43rd Street), Manhattan, NYC, New York, NY 10017.
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Article Last Updated: 08/26/2015