The
thyroid gland is a bow-tie-shaped gland, which is located at the front
of the neck, just below the Adam's apple. It produces thyroid
hormones called T3 (triiodothyronine) and T4.
The thyroid hormone regulates just about every cell in the body,
including those in the central nervous system, heart, liver, kidneys,
skin, bone, and muscles. Among its most important functions is
the control of the rate of metabolism, thermogenesis, and oxygen
consumption. The predominant thyroid hormone produced by the thyroid
gland is the relatively inactive T4. The active form
of the hormone, T3 is converted from T4by
peripheral tissues (mostly the liver) as needed.
The
secretion of these hormones is regulated by another hormone called
thyrotropin-stimulating hormone (or TSH). TSH is secreted by the
pituitary gland in a pulsatile or circadian rhythm. This
stimulating hormone activates the release of thyroid hormones from the
thyroid gland. As thyroid hormones become high (or adequate),
TSH secretion from the pituitary gland decreases in what is called a
negative feedback mechanism.
Low
thyroid function can be caused by autoimmune illnesses, such as
Hashimoto's thyroiditis, or Grave�s disease. More
commonly, low thyroid function is the effect of normal human aging.
While other hormone systems are affected by aging, the thyroid
and adrenal glands are the most stress labile glands in the body. Any
stress reduces their function. For example, a single episode of
hypoglycemia impairs thyroid function up to 18 hours. Severe stresses,
like surgery or heart attacks, affect thyroid function for months.
Moreover,
certain types of industrial and agricultural chemicals interfere with
normal thyroid metabolism. It is also speculated that other
types of environmental chemicals, such as chlorine (which is present
in the water supply) and fluoride (used in toothpaste and some types
of industrial preparations) interfere directly with the thyroid
hormone.
Hypothyroidism
(or low-functioning thyroid) can be caused by certain drug treatments,
such as alfa-interferon (which is used to treat hepatitis C) or
Amiodorone, a cardiac drug. It can also be caused by destruction
of thyroid tissue by radioactive iodine or surgery, such as would be
used to treat Graves' disease or certain types of thyroid cancer.
Nonetheless,
the gradual decline of thyroid function tends often to go
symptomatically unrecognized and is assumed to be related to the usual
aging processes. A now famous book titled Hypothyroidism:
The Unsuspected Illness, first published in 1976 by Broda Barnes,
M.D., remains an eloquent description of the clinical significance and
treatment of low thyroid function.
An
estimated 30 to 40% of women over age 40 have undiagnosed sub-clinical
hypothyroidism. That is, their laboratory test results may be
normal, yet they have true low functioning thyroids. Currently,
physicians run a blood test in order to establish a baseline of
thyroid function. The "basal body temperature" test was
developed by Broda O. Barnes, MD; Dr. Barnes believed that 40% of the
adult population suffered from thyroid deficiency. Based on the
percentage of adults now taking prescription drugs to treat
depression, elevated cholesterol, high blood pressure, and so forth,
Dr. Barnes's observations about the epidemic of thyroid deficiency may
now have been validated.
The
symptoms of low thyroid function include feeling mentally dull or
fatigued, a tendency toward depression, fluid retention, dry skin,
brittle nails, dry hair, decreased libido, decreased exercise
tolerance, decreased tolerance for any kind of emotional
stress, easy weight gain and very difficult weight loss, and elevated
cholesterol. Many individuals have all of these symptoms, but
the results of their thyroid tests are normal. However, their
true thyroid function is low. Using bio-identical natural
thyroid hormone replacement therapy in the treatment of this class of
individuals provides considerable efficacy. In fact, it can be
instrumental in literally turning their lives around.
In
individuals with symptomatic low thyroid function, thyroid replacement
therapy generally works as a very suitable, pharmacologic approach to
improving the patient's overall health. In fact, a
clinical study conducted by John Isaacs, M.D., a cardiovascular
surgeon in Baltimore, Maryland, showed that one-half of a grain of
thyroid over a ten-year period significantly improved cardiovascular
function and overall body metabolism in normally aging adults.
It
is important to start on a low dose of thyroid hormone replacement
therapy and adjust the dose at thirty-day intervals. It takes at least
30 days for the body to adjust to a new thyroid dose.
Re-evaluation of hypo- and hyper- symptoms as well as repeating
Thyroflex measurements at that time will help in adjusting dose.
Periodic tests need to be done to monitor the thyroid hormone levels.
