Download Capstone Screening Project – Hypothyroidism

Hypothyroidism is when the thyroid gland, located in the neck region, is not producing enough
of the thyroid hormone, thyroxine, or T4, to keep the body functioning properly. When the body does
not have enough thyroid hormone, the body’s processes start to slow down. Symptoms can be getting
tired, feeling cold, dry skin, feeling forgetful or depressed, and constipation (ATA, 2012). The initial
diagnosis for suspecting hypothyroidism is testing for the thyroid-stimulating hormone, or TSH. When
this is high, there is usually an indication of hypothyroidism. Follow-up laboratory testing would be
testing for thyroid hormones, to determine if these numbers are low. There are different levels of
hypothyroidism, one being subclinical hypothyroidism, which is where the TSH levels are high, but the
thyroid hormones, total thyroxine and free thyroxine, are at a normal level. Hypothyroidism and other
thyroid disorders tend to affect women more often, and the prevalence increases with age. The annual
prevalence rate for hypothyroidism in the United States is 0.08-2% in adults. Subclinical hypothyroidism
is seen in 6-8% of adult women and 3% of adult men (DiGiuseppi, 1996).
Screening for thyroid disorders is a tricky concept. According to the U.S. Preventive Services
Task Force, “the evidence is insufficient to recommend for or against routine screening for thyroid
disorders in adults (2004).” This is based off the rationale that there is no clinical benefit for early
detection and/or treatment. When one is diagnosed with true hypothyroidism, not subclinical, it is
usually permanent, meaning that treatment will most likely be required for the rest of that person’s life.
The American Thyroid Association recommends that thyroid function be tested in all adults at the age of
35 and every 5 years thereafter. More frequent screening would be recommended in high risk groups or
those who show symptoms of thyroid disease. Other standards exist among other health professional
groups that suggest screening in women over 50 who show at least one symptom of thyroid disease as
well as screening in women of childbearing age before pregnancy or during the first trimester, and that
obstetricians be aware of symptoms of thyroid disease in postpartum women. The goal of screening for
thyroid disorders is to identify and treat patients at risk for the health consequences of thyroid
dysfunction before they become clinically apparent (USPSTF, 2004).” The USPSTF found no evidence
that shows that early detection of thyroid disease leads to improved health outcomes, therefore there
are no standards in place for screening for thyroid disease.
The three main screening tests for thyroid disease are the TSH, total T4 and free T4. The
sensitivity and specificity of TSH are 98% and 92%, respectively. When used in the primary care setting,
the positive predictive value (PV+) is low. These numbers show that there can be more false positives,
possibly explaining some subclinical hypothyroidism. In fact, in some screening programs, these
patients who had high levels of TSH, but normal levels of thyroid hormones often will revert to normal
over time (USPSTF, 2004). Levels of thyroxine can be affected by a number of biological and diagnostic
factors, creating an issue for the accuracy of these tests. The specificity of free T4 can be 93-99%,
however, research has found that screening for total T4 and free T4 will produce false-positives among
healthy individuals. This makes these tests not useful for patients who do not have overt
hypothyroidism or other overt thyroid disease. “In one study, thyroid disease requiring treatment was
found in only 13% of those with abnormal FTI {a type of test of free T4} results (DiGiuseppi, 1996).”
According to recent research done by……. suggested, “apart from pregnancy, assessment of serum free
T4 should be done instead of total T4 in the evaluation of hypothyroidism…In pregnancy, the
measurement of total T4 or a free T4 index, in addition to TSH, should be done to assess thyroid status
(2012).” In terms of treatment of hypothyroidism, one should screen free and total T4, and not TSH.
Criteria for population screening include: (1) A condition that is prevalent and an important
health problem, (2) Early diagnosis is not usually made, (3) Diagnosis is simple and accurate, and (4)
Treatment is cost-effective and safe. According to recent research and the USPSTF, there has been
disagreement among expert panels about TSH screening among the general population. There is
disagreement as to when screening should start, how often it should occur, and what priority
populations should be given exception (Garber et al, 2012). This has led to different health professional
organizations putting out different standards for different populations. In terms of women in the United
States, there is consensus that hypothyroidism and other thyroid diseases are more common in women
than men and the prevalence increases with age. A lot of ethical considerations come to mind when
comparing the different standards for screening. For one, someone with overt hypothyroidism could
live for years without knowing or understanding that they have the illness, unless their primary
physician opts to screen for TSH. This can lead to mistrust of the medical community and doctors,
particularly considering hypothyroidism and most thyroid diseases cannot be cured and lifelong
treatment is recommended. There is also the issue of what has caused the hypothyroidism. In some
cases, an autoimmune thyroiditis, known as Hashimoto’s, is to blame and is the most common cause of
hypothyroidism. I, myself, was diagnosed with hypothyroidism with present of a goiter in 2005. I was
not diagnosed with Hashimoto’s, nor screened for it, until 2012. While this has not caused me any
serious harm, it has led to a change in my treatment that could have happened a long time ago, if the
medical community had set standards to follow. As an epidemiologist, because the prevalence is so low,
I wonder if it is considered a condition that is prevalent and an important health problem, as it is not a
serious condition, and it is not nearly as prevalent as other health problems such as heart disease or
cancer. This would also make it difficult to create standards for screening the general population.
When looking at the priority population I chose, being all women in the United States, I feel like
screening should begin sooner than starting at age 35. I feel that any women who show have any sort of
co-morbidity, such as pregnancy, hormonal imbalances, auto-immune disorders, and a presence of a
goiter should be screened at any age when these health conditions arise. The biggest problem with
hypothyroidism is that its symptoms can be attributed to a number of other reasons, making it difficult
to truly diagnose, based off of just one lab test alone. There is a chart I included below that shows
standards for how one can fall into overt or subclinical hypothyroidism. This chart should be used to
diagnose and determine treatment for hypothyroidism. I don’t think there would be any issues with
increasing participation in screening for hypothyroidism, as it is not a very serious illness. I think public
health should do more to make people aware of these conditions and when they should seek a doctor.
There is already a wealth of information online, but in terms of public health, I found it very disturbing
that the Centers for Disease Control and Prevention’s website didn’t have it listed as one of the
conditions you can search for. Not much needs to be done in terms of access as the screening can be
done at any lab and can be ordered by any physician or nurse-practitioner. I think more can be done
with public health to increase awareness and educate the public about how they can be screened for it
and I think it will be important to stress the differences between subclinical and overt hypothyroidism
and the issue of false positives.
References
American Thyroid Association (2012). What Is Hypothyroidism? Retrieved February 25, 2013 from
http://www.thyroid.org/what-is-hypothyroidism/
DiGiuseppi, C. (1996). Screening for Thyroid Disease. Retrieved February 25, 2013 from
http://www.ncbi.nlm.nih.gov/books/NBK15428/
Garber, J.R., Cobin, R.H., Gharib, H., Hennessey, J.V., Klein, I., Mechanick, J.I., Pessah-Pollock, R., Singer,
P.A., & Woeber, K.A. (2012). Clinical Practice Guidelines for Hypothyroidism in Adults. Thyroid,
Vol. 22 (Number 12). Retrieved February 25, 2013 from
http://www.thyroidguidelines.net/sites/thyroidguidelines.net/files/file/thy.2012.0205.pdf
Khandelwal, D. & Tandon, N. (2012). Overt and Subclinical Hypothyroidism: Who To Treat and How.
Drugs, Vol. 72 (1). Retrieved February 25, 2013 from
http://content.ebscohost.com.vproxy.cune.edu/pdf27_28/pdf/2012/C5A/01Jan12/72093863.pd
f?T=P&P=AN&K=72093863&S=R&D=aph&EbscoContent=dGJyMNLe80SeqLY4xNvgOLCmr0ueqK
9Ssam4TbaWxWXS&ContentCustomer=dGJyMOHl7Ibj2PBT69fnhrnb5ofx6gAA
National Institutes of Health (NIH) 2012). Hypothyroidism. U.S. National Library of Medicine. Retrieved
February 20, 2013 from http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001393/
U.S. Preventive Services Task Force (2004). Screening for Thyroid Disease. Retrieved February 25, 2013
from http://www.uspreventiveservicestaskforce.org/3rduspstf/thyroid/thyrrs.htm