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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 Hashimoto’s Thyroid 2 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) Hashimoto’s Thyroid 3 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 Hashimoto’s Thyroid 4 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.” Hashimoto’s Thyroid 5 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) Hashimoto’s Thyroid 6 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. Hashimoto’s Thyroid 7 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 Hashimoto’s Thyroid 8 Hashimoto’s Thyroid 9