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Running head: Hashimoto’s Thyroid
Hashimoto’s Thyroid
Epidemiology: Screening Capstone Project
Heather K. Blair
MPH 510, Epidemiology
Concordia University of Nebraska
February 20, 2014
Spring Semester
Professor: Dr. Carol Hoban
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Hashimoto’s Thyroid
Have you ever experienced any of these symptoms: fatigue, weight gain, a puffy face, joint
and muscle pain, constipation, decreased sweating, heavy or irregular menstrual periods,
impaired fertility, depression, slowed heart rate, weakness, increased difficulty losing weight,
coarse/dry hair, dry/rough pale skin, hair loss, cold intolerance (you can't tolerate cold
temperatures like those around you), muscle cramps, irritability, memory loss, and decreased
libido (Norman, 2012)? If you have, you may have a hormone deficiency produced by your
thyroid gland, known as Hashimoto’s Thyroid or hypothyroidism.
The thyroid gland, which is part of the endocrine system, releases a hormone that sets the
body’s thermostat for a healthy metabolism. The thyroid gland is approximately 2 inches long
and sits in the front of the neck below the voice box. It has 2 lobes, one on each side of the wind
pipe. This gland is responsible for making two hormones – T3 and T4. The production of these
hormones is regulated by the pituitary gland which produces thyroid-stimulating hormone
(TSH).
(NIDDK, 2013)
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Changes in thyroid function either up (over active - hyper) or down (under active hypo) can have a negative effect on the overall function of the body. There are about six known
causes of hypothyroidism: Hashimoto’s Disease, thyroiditis – inflammation of the thyroid,
congenital hypothyroidism – present at birth, surgical removal of part or all of the thyroid,
radiation treatment of the thyroid and some medications (NIDDK, 2013). The most common
type of hypothyroidism is from chronic inflammation of the thyroid, which causes a failure of the
whole or part of the thyroid gland which is initiated from an individual’s own immune system;
this is known as Hashimoto’s Disease or autoimmune thyroiditis (Norman, 2012). The second
most common form of hypothyroidism is from medical interventions – radiation treatment,
medication, and surgical removal (Norman, 2012).
As mentioned above, there are a variety of symptoms that may be associated with
hypothyroidism. Many people may only exhibit a small number of these symptoms and some
people are asymptomatic and may not even realize that they do not have an optimal thyroid
function. There are generally four blood tests that can be done to confirm the clinical diagnosis
of hypothyroidism – TSH, T3, T4 and thyroid antibodies (NIDDK, 2013). These tests most often
are ordered in combination with each other (Lab Testing Online, 2013).
The TSH or Thyrotropin test is the blood test that is most often used to diagnose
hypothyroidism or hyperthyroidism (Lab Testing Online, 2013). The TSH range for a normal
functioning thyroid is 0.4 - 4.0 mIU/L (NIH, 2012). When TSH test results are high, it is often
an indication of hypothyroidism and when they are low, it usually means that a person has
hyperthyroidism. Either way, high or low, it is a positive indication that there is a thyroid
dysfunction that requires further investigation. This test does not advise the clinician as to the
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root of the dysfunction, only that one is present (Lab Testing Online, 2013). In a report by the
USPSTF (2004), it notes the sensitivity (98%) and a specificity of (92%) for the high sensitivity
TSH test, but it goes on to further note that the positive predictive value (PPV) of TSH is low
0.06%. There are two more tests the - T4 thyroid hormone for thyroxine, which has a normal
range of 4.5 to 11.2 mcg/dL and the T3 thyroid hormone for Triiodothyronine, which has a
normal range of 100 - 200 ng/dL both of these test when high or low are used in the diagnosis of
thyroid disorders (NIH, 2013) The table below shows how the TSH, T4 and T3 tests may be
interpreted:
TSH
High
T4
Normal
T3
Interpretation
Normal
Mild (subclinical) hypothyroidism
Low or
High
Low
Hypothyroidism
normal
Low
Normal
Normal
Mild (subclinical) hyperthyroidism
High or
High or
Low
Hyperthyroidism
normal
normal
Low or
Low or
Non-thyroidal illness; rare pituitary (secondary)
Low
normal
normal
hypothyroidism
(Lab Testing Online, 2013) http://labtestsonline.org/understanding/analytes/tsh/tab/test
The thyroid antibodies test is primarily used to diagnose the autoimmune variety of
thyroid disorders, including goiter (Lab Testing online, 2013). With this test, it looks for
antibodies in the blood, if they are present, the thyroid disorder could be a result of an
autoimmune variety, whereas if they are not present, it rules out an autoimmune origin (Lab
Testing Online, 2013). There seems to be no clear sensitivity or specificity for the thyroid
antibody testing, but Lab Testing Online (2013), states “The sensitivity and specificity of thyroid
antibody testing is improving but is still not as good as doctors would like it to be. All of the
thyroid antibody tests have changed over time.”
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The treatment for hypothyroidism is usually very simple for most people; they are able to
take a synthetic thyroid hormone that mimics the body’s naturally occurring T4 hormone. The
synthetic hormone is thyroxine, which is usually taken once a day, in the morning and monitored
on a regular basis with blood work every six months to once a year to maintain an individual’s
optimum levels (NIDDK, 2013).
It has been estimated that over 10 million Americans have this all too common medical
condition (Norman, 2012). Norman (2012), further estimates that over 10% of women have
some sort of thyroid hormone deficiency. Hypothyroidism can affect anyone, but tends to affect
women more often and people over the age of 60 years old (NIDDK, 2013). There seems to be
no concrete recommendations on when to begin screening for hypothyroidism (Garber, et al.,
2012). The table below shows screening recommendations from six different organizations:
Table 8
Recommendations of Six
Organizations Regarding Screening of
Asymptomatic Adults for Thyroid
Dysfunction
Organization
Screening recommendations
American Thyroid Association
Women and men >35 years of age should be
screened every 5 years.
American Association of Clinical Endocrinologists
Older patients, especially women, should be
screened.
American Academy of Family Physicians
American College of Physicians
U.S. Preventive Services Task Force
Royal College of Physicians of London
Patients ≥60 years of age should be screened.
Women ≥50 years of age with an incidental
finding suggestive of symptomatic thyroid
disease should be evaluated.
Insufficient evidence for or against screening
Screening of the healthy adult population
unjustified
(Garber, et al., 2012)
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When considering a screening protocol for thyroid disorders the criteria should recognize
that hypothyroidism is a disorder that is prevalent and can have considerable health effects, early
diagnosis is often not made until symptoms are very apparent, diagnosis can be fairly simple and
accurate and the treatment to maintain normal levels is cost effective and safe (Garber, et al,
2012). From a public health perspective awareness is key – individuals and doctors need to have
the most current information available. Increased awareness could be brought about through
public service announcements, posters/flyers at healthcare offices, and the internet can be a great
resource for people.
With the current information available, it would seem that primary care doctors,
obstetricians, pediatricians, and mental health care providers all need to be aware of the signs
and symptoms of thyroid disorders. They should recommend these simple blood tests to anyone
complaining of symptoms that are associated with hypothyroidism. Hashimoto’s thyroid disease
can not be cured, but can be maintained with the correct dosage of daily medication, regular
blood work and follow up with an individual’s doctor.
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References
Garber, J. R., Cobin, R. H., Gharib, H., Hennessey, J. V., Klein, I., Mechanick, J. I., . . Woeber,
K. A. (2012). Clinical practice guidelines for hypothyroidism in adults: cosponsored by
the American association of clinical endocrinologists and the American thyroid
association. Endocrine Practice, 18(6), 989-1028.
Lab Test Online. (2013). TSH. Retrieved from
http://labtestsonline.org/understanding/analytes/tsh/tab/test
Lab Test Online. (2013). Thyroid Antibodies. Retrieved from
http://labtestsonline.org/understanding/analytes/thyroid-antibodies/tab/test
NIDDK. (2013). Hypothyroidism. Retrieved from
http://endocrine.niddk.nih.gov/pubs/Hypothyroidism/
NIH. (2014). T3 Test. Retrieved from
http://www.nlm.nih.gov/medlineplus/ency/article/003687.htm
NIH. (2014). T4 Test. Retrieved from
http://www.nlm.nih.gov/medlineplus/ency/article/003517.htm
NIH. (2012). TSH Test. Retrieved from
http://www.nlm.nih.gov/medlineplus/ency/article/003684.htm
Norman, J. (2012). Hypothyroidism: Too Little Thyroid Hormone. Retrieved from
http://www.endocrineweb.com/conditions/thyroid/hypothyroidism-too-little-thyroidhormone
USPSTF. (2004). Screening for Thyroid Disease. Retrieved from
http://www.uspreventiveservicestaskforce.org/3rduspstf/thyroid/thyrrs.htm
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