MEAGHAN MOLLARDNUR 668

Hypothyroidism

(Luzy, 2009)

ICD9 Codes

244.1 Other post-ablative hypothyroidism244.8 Other specified acquired

hypothyroidism244.9 Unspecified acquired hypothyroidism

(Domino, 2014)

Definition of Hypothyroidism

UNDERACTIVE THYROIDAffects:

Metabolic and endocrine systemsClinical 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 glandLocated at the base of the neck, below the

larynx and above the claviclesLocated 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 Primary

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

Secondary 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

HyponatremiaAnemiaIdiopathic

adrenocorticoid deficiency

Diabetes mellitusHypoparathyroidismMyasthenia gravisVitiligo

HypercholesterolemiaMitral valve prolapseDepressionRapid-cycling bipolar

disorderIschemic heart

diseaseMetabolic SyndromeDown syndromeCeliac Disease

(Domino, 2014)

Incidence

Predominant age: >40 yearsPredominant gender: Female>Male, 5-10:1More common in women with small body size

at birth and during childhood

(Domino, 2014 ; Ross, 2014)

Prevalence

3.7% of general population18 cases per 1,000 persons in the general

populationSubclinical 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

thereafterThe 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 60Family history of thyroid diseasePregnancyUse of medications that may impair thyroid

functionHistory of goiterAutoimmune disease or type 1 diabetesPrevious thyroid surgeryPrevious treatment with radioactive iodine therapy

or anti-thyroid medicationsRadiation 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

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: 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: 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 newbornsCaused 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

AnemiaDementiaChronic heart failureKidney failureAutoimmune Thyroid

DiseasePregnancyConstipationDepressionDysmenorrheaFibromyalgia

Euthyroid Sick SyndromeGoiterMyxedema Coma or CrisisRiedel ThyroiditisSub-acute ThyroiditisThyroid LymphomaIodine DeficiencyAddison DiseaseAnovulationApneaChronic 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: 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 restEliminate emotional stressModerate exercise for stress controlEat 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 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 stateRelapse will occur if treatment interruptedIf untreated, may progress to myxedema

coma

(Domino, 2014)

Complications

GoiterHeart problemsMental health issuesIncreased susceptibility to infectionMegacolonSexual dysfunctionOrganic psychosis with paranoiaAdrenal crisisInfertilityHypersensitivity to opiatesLong-term treatment leads to bone demineralizationMyxedema coma->MEDICAL EMERGENCY!

(Domino, 2014 ; MayoClinic, 2012)

Complications of Hypothyroidism during Pregnancy

PreeclampsiaAnemiaPostpartum hemorrhageCardiac ventricular dysfunctionIncreased risk of spontaneous abortionLow birth weightImpaired cognitive developmentFetal mortality

(Ross, 2014)

Follow-up

Monitoring depends on the underlying causesMonitor TSH:

Initially after 6 weeks of therapy -> Q6-12 weeks until stabilized-> annually

Follow cardiac status closely in older patientsCheck 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 replacement therapy

Explain need for lifelong treatmentInstruct to report any signs of infection or heart

problemsEducate of the signs of thyrotoxicityEducate high-bulk may help avoid constipationEducate 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/hypothyroidism-underactive-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: 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? 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? 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? 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? 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? 1. Thyroid stimulating hormone 2. T3 3. T4

Answer with Rationale

3. T4Standard 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? 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? 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

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/health-and-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/122393-overview#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.