Hypothyroidism
MEAGHAN MOLLARD
NUR 668
(Luzy, 2009)
ICD9 Codes
 244.1 Other post-ablative hypothyroidism
 244.8 Other specified acquired hypothyroidism
 244.9 Unspecified acquired hypothyroidism
(Domino, 2014)
Definition of Hypothyroidism
 UNDERACTIVE THYROID
 Affects:
 Metabolic and endocrine systems
 Clinical state resulting from decreased circulating
levels of free thyroid hormone produced by the
thyroid gland OR resistance to the action of the
thyroid hormone
(Domino, 2014 ;Hollier & Hensley, 2011 MayoClinic, 2012)
Anatomy
 Small, butterfly shaped gland
 Located at the base of the neck, below the larynx and
above the clavicles
 Located below Adam’s apple in men
(MayoClinic, 2012 ; WebMD, 2014)
Pathophysiology
 Thyroid gland produces hormones:
 Triiodothyronine (T3)
 Thyroxine (T4)
Both impact metabolism- maintaining the rate at which the body
uses fats and carbs
 Regulates how the body uses and stores energy
 Controls body temperature
 Influences heart rate
 Helps to regulate the production of proteins

(MayoClinic, 2012 ; Ross, 2014 ; Orlander, 2014)
Etiology
 Hypothyroidism is broadly classified as a primary,
secondary, or tertiary disease depending on the
underlying cause
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Primary
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Secondary
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there is impaired hormone release from the thyroid gland
 Causes: Hashimoto’s thyroiditis, iatrogenic, congenital, subacute
thyroiditis, sub-acute thyroiditis, iodine deficiency, medications,
and postpartum thyroiditis
there is defective TSH signaling from the pituitary
 Causes: Hypopituitarism, Sheehan Syndrome, Pituitary tumors
Tertiary or Central

the hypothalamus fails to stimulate thyroid hormone release
 Cause: Hypothalamic dysfunction
(Domino, 2014)
Commonly Associated Conditions
 Hyponatremia
 Hypercholesterolemia
 Anemia
 Mitral valve prolapse
 Idiopathic
 Depression
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adrenocorticoid
deficiency
Diabetes mellitus
Hypoparathyroidism
Myasthenia gravis
Vitiligo
 Rapid-cycling bipolar
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disorder
Ischemic heart disease
Metabolic Syndrome
Down syndrome
Celiac Disease
(Domino, 2014)
Incidence
 Predominant age: >40 years
 Predominant gender: Female>Male, 5-10:1
 More common in women with small body size at
birth and during childhood
(Domino, 2014 ; Ross, 2014)
Prevalence
 3.7% of general population
 18 cases per 1,000 persons in the general population
 Subclinical hypothyroidism: 4-20%
 Common in elderly
(Domino, 2014 ; Orlander, 2014)
Screening Recommendations
 Routine screening of all newborn babies in the
United States
 No universal screening recommendations for adults

Two strategies for screening asymptomatic patients:
1. Screen all individuals over a certain age, when risk of
hypothyroidism increases
 2. Screen only those with clinical risk factors.

(Orlander, 2014 ; Ross, 2014)
Specific Screening Recommendations
 The American Thyroid Association:
 All patients over the age of 35 and every 5 years thereafter
 The American College of Physicians:
 All women older than 50 years who have 1 or more clinical
features of the disease
 The American Academy of Family Physicians:
 Asymptomatic patients older than 60 years
 The American Association of Clinical
Endocrinologists:

TSH measurements in all women of childbearing age before
pregnancy or during the first trimester
(Orlander, 2014)
Screening Indications
 Women older than 60
 Family history of thyroid disease
 Pregnancy
 Use of medications that may impair thyroid function
 History of goiter
 Autoimmune disease or type 1 diabetes
 Previous thyroid surgery
 Previous treatment with radioactive iodine therapy
or anti-thyroid medications
 Radiation therapy to head, neck or upper chest
(MayoClinic, 2012 ; Ross, 2014)
Risk Factors
Women >60 years
Increasing age
Family History
Personal or family history of autoimmune diseases, including type 1
diabetes mellitus (DM), Addison disease
 Previous postpartum thyroiditis
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OR pregnant or delivered baby within last 6 months
Previous head or neck irradiation
History of thyroid surgery
Treatment hyperthyroidism
Hypothalmic disease
Pituitary disease
History of Graves disease
Treatment with lithium, immune modulators, or iodine containing
antiarrhythmic amiodarone
(Domino, 2014 ; Hollier & Hensley, 2011)
Subjective Clinical Findings
 History:
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Onset insidious, subtle
Weakness, fatigue, lethargy
Cold intolerance
Decreased memory and concentration
Hearing impairment
Constipation
Muscle cramps
Modest weight gain (10lbs)
Swelling in hands and feet
Decreased sweating
Menorrhagia, decreased libdo, infertility
Depression
Hoarseness
(Domino, 2014 ; WebMD, 2014)
Objective Clinical Findings
 Physical Exam:
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Dry coarse skin
Dull facial expression
Coarsening or huskiness of voice
Periorbital puffiness
Swelling of hands and feet (nonpitting)
Bradycardia
Hypothermia
Reduced systolic BP
Increased diastolic BP
Reduced body and scalp hair
Delayed relaxation of deep-tendon reflexes
Macroglossia
(Domino, 2014 ; 24Remedy, 2015)
(Brownstein, 2015)
Hypothyroidism in Infants
 Affects 1 in every 4000 newborns
 Caused by:
 Lack of thyroid gland
 Dysfunctional gland

Signs and Symptoms:
 Jaundice
 Choking
 Enlarged, protruding tongue
 Puffy face
 Constipation
 Poor muscle tone
 Excessive sleepiness
(MayoClinic, 2012 ; Orlander, 2014)
Hypothyroidism in Children and Teens
 S/S similar to adults
 In addition..
Poor growth-> short stature
 Delayed puberty
 Poor mental development

(MayoClinic, 2012)
Differential Diagnosis
 Anemia
 Euthyroid Sick Syndrome
 Dementia
 Goiter
 Chronic heart failure
 Myxedema Coma or Crisis
 Kidney failure
 Riedel Thyroiditis
 Autoimmune Thyroid
 Sub-acute Thyroiditis
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Disease
Pregnancy
Constipation
Depression
Dysmenorrhea
Fibromyalgia
 Thyroid Lymphoma
 Iodine Deficiency
 Addison Disease
 Anovulation
 Apnea
 Chronic Fatigue Syndrome
(Domino, 2014 ; Orlander, 2014)
Social and Environmental Considerations
 No specific diets are required for hypothyroidism
 Dose may need to be increased if thyroid disease
worsens:
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During pregnancy
Gastrointestinal conditions that impair T4 absorption
Weight gain
Aluminum containing antacids, high fiber diets, and iron
tablets can interfere with T4 absorption
(Ross, 2014)
Diagnosis
 Based on:
 1. Symptoms
 2. Blood tests
TSH-thyroid stimulating hormone
 T4-thyroxine
 Serum TSH normal – no further testing performed
 Serum TSH high -> Free T4 to determine degree of disease

(MayoClinic, 2012)
Laboratory Tests
 Initial lab tests:
 Subclinical hypothyroidism
TSH elevated (>4.5mlU/L)
 Serum free T4 normal


Primary hypothyroidism
TSH elevated (>4-5mU/L)
 Serum free T4 decreased


Severe hypothyroidism
Anemia
 Elevated Cholesterol
 Elevated creative phosphokinase, lactate dehydrogenase, aspartate
aminotransferase

(Domino, 2014)
Imaging
 Initial approach:
 None necessary, unless signs or cardiac involvement
 Chest radiograph may show enlarged heart (pericardial
effusion)
(Domino, 2014 ; Gupta & Ammini, 2012)
Prevention
 Monitoring for those being treated for
hyperthyroidism
 Newborn T4screening at 2-6 days of age.
Management/ Treatment
 Goal of treatment include:

Return blood levels of TSH and T4 to the normal range

Alleviate symptoms

Decision to treat subclinical hypothyroidism is controversial

Typically treated if TSH is >10mU/L to prevent symptom
development
(Ross, 2014)
Non-pharmacological
 Adequate rest
 Eliminate emotional stress
 Moderate exercise for stress control
 Eat a well balanced diet
 High in fiber to prevent constipation
 Low fat for weight reduction
 Annual lipid level assessment
(Cornille, 2004)
Pharmacologic
 Standard treatment:
 Oral form of T4- synthetic thyroid hormone
 Administered to supplement or replace exogenous production
 Given once daily on an empty stomach – at least one hour
before eating or two hours after eating
Levothyroxine
 Levothroid
 Synthroid
 Levoxyl
 Unithyroid


PREFERABLE TO STAY ON SAME TYPE OF T4
(Ross, 2014)
Pharmacologic Management
 Prescribe an initial dose of T4

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Start hormone replacement for healthy adults at 1.6mcg per
kg/day ->with a typical maintenance dose between 50-200mcg/d
depending on disease severity and underlying cause
->Retest TSH in 6 weeks

->T4 dose can be adjusted depending on results
 -> This process may need to be repeated several times before
hormone level returns to normal
• -> Once optimal dose identified recommended monitoring yearly
• NEVER OVER REPLACE T4
 -> Can cause mild hyperthyroidism which can increase the risk
for Afib and accelerate bone loss
(Kansagra, McCudden & Willis, 2010; Ross, 2014)
Prognosis
 Return to normal state
 Relapse will occur if treatment interrupted
 If untreated, may progress to myxedema coma
(Domino, 2014)
Complications
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Goiter
Heart problems
Mental health issues
Increased susceptibility to infection
Megacolon
Sexual dysfunction
Organic psychosis with paranoia
Adrenal crisis
Infertility
Hypersensitivity to opiates
Long-term treatment leads to bone demineralization
Myxedema coma->MEDICAL EMERGENCY!
(Domino, 2014 ; MayoClinic, 2012)
Complications of Hypothyroidism during
Pregnancy
 Preeclampsia
 Anemia
 Postpartum hemorrhage
 Cardiac ventricular dysfunction
 Increased risk of spontaneous abortion
 Low birth weight
 Impaired cognitive development
 Fetal mortality
(Ross, 2014)
Follow-up
 Monitoring depends on the underlying causes
 Monitor TSH:
 Initially after 6 weeks of therapy ->

Q6-12 weeks until stabilized-> annually
 Follow cardiac status closely in older patients
 Check TSH more frequently in the setting of:
 Pregnancy
 Initiation of estrogen supplementation
 After large changes in body weight
 In central hypothyroidism, TSH unreliable
 Monitor free T4, T3
(Domino, 2014)
Counseling/Education
 Stress the importance of compliance with thyroid
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replacement therapy
Explain need for lifelong treatment
Instruct to report any signs of infection or heart
problems
Educate of the signs of thyrotoxicity
Educate high-bulk may help avoid constipation
Educate about signs and symptoms of overtreatment

Tachycardia, palpitations, Afib, nervousness, tiredness,
headache, increased excitability, sleeplessness, tremors,
possible angina
(Domino, 2014)
Patient Resources
 “The Basics”
 “Beyond the Basics”
 http://www.uptodate.com/contents/hypothyroidismunderactive-thyroid-beyond-the-basics?source=see_link
(Ross, 2014)
Consultation/Referral
 Suspected myxedema coma is a medical emergency
with a high risk of mortality!
 Indications for referral to an endocrinologist:
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Nodular thyroid, suspicious thyroid nodules or compressive
symptoms (Ex: dysphagia)
Pregnancy
Underlying cardiac disorder or other endocrine disorders
Age younger than 18 years
Secondary or tertiary hypothyroidism
Unusual constellation of thyroid function test results
Inability to maintain TSH in target range
Unresponsiveness to treatment
(Orlander, 2014)
Expected Course
 Improvement expected 2-weeks after initiation of
medication therapy
 Signs and symptoms should resolve in 3 to 6 months
 Lifelong therapy needed
(Hollier & Hensley, 2011)
Question 1
 Hypothyroidism affects what body systems?
 1. Respiratory and endocrine
 2. Cardiac and metabolic
 3. Metabolic and integumentary
 4. Metabolic and endocrine
Answer with Rationale
 4. Metabolic and endocrine systems
Question 2
 Which individual is at the highest risk for
hypothyroidism?
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1. 67 y.o., white, female
2. 28 y.o., white, male
3. 50 y.o., black, female
4. 70 y.o., hispanic, male
Answer with Rationale
 1. 67 y.o., white, female
 Increased risk with advanced age >60 y.o.
 More common in whites (5.1%), African Americans tend to
produce less TSH than white
 Hypothyroidism 5-10x more common in women than men
Question 3
 What is the starting replacement dose of T4 in a
healthy adult?
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1. 2.4 mcg/kg/day
2. 1.6 mcg/kg/day
3. 1.2 mcg/kg/day
4. 0.4 mcg/kg/day
Answer with Rationale
 2. 1.6 mcg/kg/day
 60kg patient

1.6mcg/kg/day
 96mcg/day-> 100mcg tablet QD
(Kansagra, McCudden & Willis, 2010)
Question 4
 Most effective treatment regime for managing
hypothyroidism?
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1. Balanced diet and adequate fluid intake
2. Synthetic hormone replacement therapy
3. Regular exercise and adequate rest
Answer with Rationale
 2. Synthetic hormone replacement
 Best treatment, balanced diet, adequate rest, and exercise
regime are all non-pharmocological measures for managing
hypothyroidism. There is no other method for complete
management besides a synthetic hormone.
Question 5
 3 common symptoms of hypothyroidism include:
 1. Weight gain, cold intolerance, dry skin
 2. Heat intolerance, excessive sweating, and palpitations
 3. Fatigue, difficulty concentrating, weight loss
 4. Increased blood pressure, high pitched voice, constipation
Answer with Rationale
 1. Weight gain, cold intolerance, and dry skin
Question 6
 What is the most common cause of primary
hypothyroidism?
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1. Subacutethyroiditis
2. postoperative thyroidectomy
3. post-ablative therapy
4. Hashimoto’s thyroiditis
Answer with Rationale
 4. Hashimoto’s thyroiditis
 Most common cause of hypothyroidism in the U.S., with an
incidence of 3.5 cases per 1,000 women per year and 0.8 cases
per 1,000 men per year
Question 7
 Most common synthetic hormone used to treat
hypothyroidism?
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1. Thyroid stimulating hormone
2. T3
3. T4
Answer with Rationale
 3. T4
 Standard treatment:
 Administered to supplement or replace endogenous
production
 Oral form of T4- synthetic thyroid hormone
Question 8
 What gland produces TSH, which stimulates the
production of T3 and T4?
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1. Thyroid gland
2. Pituitary gland
3. Adrenal gland
4. Thymus gland
Answer with Rationale
 3. Pituitary gland
 The thyroid is controlled by the pituitary gland, producing
TSH, stimulating the thyroid to produce T 3 and T4
Question 9
 TSH and T4 levels in primary hypothyroidism
 1. Elevated TSH and elevated free T4
 2. Elevated TSH and decreased free T4
 3. Decreased TSH and elevated free T4
 4. Decreased TSH and decreased free T4
Answer with Rationale
 2. Elevated TSH and decreased free T4
 Primary hypothyroidism
TSH elevated (>4-5mU/L)
 Serum free T4 decreased

Question 10
 When screening for hypothyroidism, what is the
initial blood test?
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1. Free T4
2. T3
3. TSH
4. All of the above
Answer with Rationale
3
Serum TSH normal – no further testing performed
 Serum TSH high -> Free T4 to determine degree of disease

References
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24Remedy. (2015). Identifying the symptoms of hypothyroidism & how to prevent them. Retrieved on January 10, 2015 from
http://www.24remedy.com/health-care/symptoms-of-hypothyroidism/.
Brownstein, D. (2015). The thyroid gland. Retrieved on January 10, 2015 from http://www.celticseasaltblog.com/articles/healthand-fitness/the-thyroid-gland/.
Cornille, A. (2004). Thyroid hormones, symptoms, and treatments for hypothyroidism. Retrieved on January 20, 2015 from
http://www.project-aware.org/Resource/articlearchives/thyroid.shtml.
Luzy, R. (2009). Difference between hypothyroidism and hyperthyroidism. Retrieved on January 10, 2015 from
http://www.differencebetween.net/science/health/difference-between-hypothyroidism-and-hyperthyroidism/.
Domino, F.J. (2014). 5 Minute clinical consult 2014. Lippincott Williams & Wilkins.
Gupta, Y., & Ammini, A.C. (2012). Vitiligo, hypothyroidism and cardiomyopathy. Indian Journal of Endocrinology and
Metabolism, 16(3): 463-465.
Hollier, A. & Hensley, R. ( 2011). Clinical Guidelines in Primary Care: A Reference and Review Book. Lafayette, LA: Advanced
Practice Education Associates, Inc.
Kangsagra, S.M., McCuden, C.R., & Willis, M.S. (2010). The challenges and complexities of thyroid hormone replacement.
LabMedicine: 41(6): 229-348.
MayoClinic. (2012). Hypothyroidism (underactive thyroid). Retrieved on January 7, 2015 from
http://www.mayoclinic.org/diseases-conditions/hypothyroidism
Orlander, P.R. (2014). Hypothyroidism. Retrieved on January 19, 2015 from http://emedicine.medscape.com/article/122393overview#a0156.
Ross, D.S. (2014). Patient information: hypothyroidism (underactive thyroid) (beyond the basics). Retrieved on January 20,
2015 from http://www.uptodate.com/contents/hypothyroidism-underactive-thyroid-beyond-the-basics.
Ross, D.S. (2014). Diagnosis of and screening for hypothyroidism in nonpregnant adults. Retrieved on January 20, 2014 from
http://www.uptodate.com/contents/diagnosis-of-and-screnning-for-hypothyroidisn-in-nonpregnantaduts
WebMD. (2014). Women’s health. Retrieved on January 10, 2015 from http://www.webmd.com/women/picture-of-the-thyroid.
WebMD. (2013). Hypothyroidism (underactive thyroid). Retrieved on January 7, 2015 from
http://www.webmd.com/women/hypothyroidism-underactive-thyroid-symptoms-causes-treatments.