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Flashcards in week 8- hyper and hypo thyroidism Deck (42)

The thyroid makes thyroid hormone (T3 & T4)

Controls metabolism
Balances calcium and phosphorus
Regulated by the Hypothalmic-Pituitary-Thyroid negative feedback loop
Need dietary intake of protein & iodine to produce TH
Thyroid hormones affect all body cells, specifically:
---Effects on growth, metabolic rate and specific body mechanisms
---T3 & T4 increase metabolism=increased O2 consumption and heat production in all tissues (Iggy, 2010)


conversion of T'S

T4 converts to T3 in the cell
Conversion is impaired by: stress, starvation, dyes, beta blockers, amiodarone, corticosteroids, and PTU


Functions of TH

Fetal development
Control metabolic rate
Growth hormone and gonadotropins (pituitary)
Regulates protein, carb and fat metabolism
Chronotropic and inotropic cardiac effects (rate and force of contraction)
Increases RBC production
Affects resp rate and drive
Increases bone formation and decreases bone resorption of calcium (through calcitonin release)
Acts as insulin antagonist


Thyroxine (T4)

-influences metabolic rate, regulates lipid & carbohydrate metabolism


Triiodothyronine (T3)-

help regulate growth development, metabolism and controls heat regulation (thermoregulating center)



responds to hypercalcium, lowers plasma calcium and phosphate levels, inhibits reabsorption of calcium into bones

Responsible for maintaining adequate levels of calcium in the extracellular fluid


Thyroid gland communicates with parathyroid gland that lies above and behind it.

Iodine and tyrosine(amino acid) is essential for proper functioning of thyroid glands which generally is acquired in sufficient amounts from our diet.
T3 &T4 are stored with thyrogloblin (a protein that contains tyrosine and amino acid) in the follicles in the thyroid gland called colloids
When thyroid gland is signaled it will release T3 & T4 into the circulation system. Low blood level will trigger TSH (thyroid stimulating hormone) known as thyrotropin.


Negative Feedback Loop

Hypothalamus produces and secretes thyrotropin-releasing
hormone (TRH)
TRH stimulates the anterior pituitary to secrete thyroid stimulating hormone (TSH)
TSH stimulates the thyroid gland to increase production of
T3 (triiodothyronine) and T4 (thyroxine)


neg feedback looop

If the thyroid hormone (T3 & T4) levels get too high, the hypothalamus decreases secretion of TRH and the pituitary decreases secretion of TSH

If the thyroid hormone (T3 & T4) levels get too low, the hypothalamus increases secretion of TRH and the pituitary increases secretion of TSH
Hyperthyroid = HIGH T3 & T4 and LOW TSH
Hypothyroid=LOW T3 & T4 and HIGH TSH


Thyroid Disease

 Hypothyroidism more common that hyperthyroidism
 Women affected > men
 Symptoms of thyroid disease extremely variable
 New onset or a change in symptoms important
 May develop quickly or slowly
 Only blood tests confirm diagnosis
 Iodine deficiency in undeveloped countries most common cause of hypothyroidism = goiter (enlarged thyroid gland)
 Iodine added to salt in many countries


Thyroid Disease: Causes

-Primary Causes
 Autoimmune disorders
 Graves’ Disease (hyperthyroidism)
 Hashimoto’s Thyroiditis (hypothyroidism)
• Secondary Causes
 Pituitary tumours, surgery, irradiation, medications
 Plummer’s disease (toxic nodular disease “hot nodule”)
 Multinodular disease


Graves’ disease affects mostly women and between age




 Low energy
 Fatigue-trouble awakening in am, need more sleep, falls asleep during the day
 Feeling cold when others feel warm
 Less sweating
 Dry, itchy skin
 Dry, coarse, brittle hair
 Increased hair loss (thinner)
 Loss of outer third of eyebrow
 Loss of appetite
 Mild weight gain (5-15 lbs), difficulty losing weight ** does not cause obesity
 New or worsening memory problems and slowed thinking
 New snoring
 More frequent muscle cramps and joint aches
 New feeling of pins and needles in hands and feet (parasthesia)
 New constipation
 New puffiness around the face (especially eyes), hands, feet and ankles
 Carpal tunnel
 Heavier and/or more frequent periods, worse cramps, worse premenstrual symptoms
 Feeling irritable
 New depression
 New hoarse voice
 New hearing loss
 Goiter (enlarged thyroid gland)-most common with Hashimoto’s thyroiditiis
 Shrinking thyroid
 Decreased HR-decreased blood flow and O2 delivery to tissues
 Slight increase in BP
 Higher cholesterol levels
 Slow reflexes
 Heat intolerance*
 Diaphoresis/smooth moist skin
 Hair loss
 Weight loss with increased appetite
 Nervousness & tremors
 Palpitations, tachycardia, Atrial fib
 Insomnia
 Goiter
 Menstrual irregularities (-)
 Hypertension
 Frequent bowel movements*



 Cold intolerance
 Dry coarse skin
 Hair loss
 Weight gain with poor appetite
 Fatigue/lethargy
 Bradycardia
 Hypersomnia
 Goiter
 Menstrual irregularities (+)
 Slow thinking/memory
 Constipation*
 Tachycardia/palpitations
 Chest pain
 Increased SBP
 Dysrhythmias
 Muscle weakness/wasting
 Blurred or double vision
 Eye fatigue
 Corneal ulcers or infections
 Increased tears/redness/photophobia
 Eyelid retraction/eyelid lag**Graves’ disease only
 Globe lag** Wide-eyed startled look
 Hyperactive tendon reflexes
Low grade fever



 When patient reports general symptoms of fatigue or unplanned weight change and depression or anxiety, be sure to ask about other S &S related to thyroid disorders that they may not automatically mention
 Nutrition, elimination, sleep-rest pattern, sexuality-reproductive & activity-exercise assessments (Iggy, 2010)
 Head-to-toe assessment-affects all body systems
 Inspect and palpate thyroid gland (See Jarvis*not usually part of a routine nursing assessment)
 Review diagnostic test results
 Discuss life impact (ie: work, activity, relationships)
 When patient reports general symptoms of fatigue or unplanned weight change and depression or anxiety, be sure to ask about other S &S related to thyroid disorders that they may not automatically mention
 Nutrition, elimination, sleep-rest pattern, sexuality-reproductive & activity-exercise assessments (Iggy, 2010)
 Head-to-toe assessment-affects all body systems
 Inspect and palpate thyroid gland (See Jarvis*not usually part of a routine nursing assessment)
 Review diagnostic test results
 Discuss life impact (ie: work, activity, relationships)


Diagnostic Testing

• TSH is the most sensitive test of thyroid function
o Decreased TSH = hyperthyroidism
o Increased TSH = hypothyroidism
• T4 testing may help differentiate sub-clinical (mild)disease
• Imaging tests-ultrasound, Radioactive Iodine Scan
• Fine needle biopsy
• CBC, lipid profile, metabolic profile

Ultrasound: info about solid vs cystic nodules, info about benign vs malignant tumours (looks at border edges, vascularity, presence of microcalcifications),
RAI Scan: identify whether nodule is “hot” (more likely benign) or “cold” (more likely malignant)

Pts with hypothyroidism may also have iron deficiency anemia, dyslipidemia, hyponatremia, and decrease GFR


Toxic Nodular Disease “hot nodule”

• This scan shows a solitary "hot" nodule located in the left lobe
• This single nodule is comprised of thyroid cells which have lost their regulatory mechanism that dictates how much hormone to produce
• Without this regulatory control, the cells in this nodule produce thyroid hormone at a dramatically increased rate causing symptoms of hyperthyroidism
• Some nodules are "cold" since they
o don't produce any hormone at all


Risk Factors: Hypothyroidism

Family history
Personal history of thyroid disease
Women over 50 & the elderly
History of autoimmune diseases
6 weeks to 6 months postpartum or during menopause
White or Asian

One of the most common thyroid disorders
Affects people worldwide regardless of age, sex, race, wealth, education
Almost half of people with hypothyroidism don’t know it


Treatment: Hypothyroidism

• Synthetic thyroid hormone replacement for life
• Levothyroxine once daily
• Long half-life (7 days)
• Dose slowly increased until thyroid hormone levels normal
• Goal of thyroid replacement therapy is to keep TSH in the low normal range (euthyroid)
• Dosage based on age, weight, and cardiac status
• **use caution in patients with cardiac disease
• *Bowel movement regularity an important guide to therapeutic effect
• Full effect expected in 4-6 weeks


Patient Teaching: Hypothyroidism Treatment

Levothyroxine absorption affected by:
• Dietary fibre
• Antacids
• Iron
• Calcium
• Take with full glass of water
• Best one hour before breakfast
• Same time daily
• Consult HCP before taking other OTC medications
• **over-replacement is biggest problem (know hyper S & S!)
• Do not stop taking abruptly – causes rebound effects
• Monitor for CV disease and symptoms
• Use cautiously with Coumadin*report bruising or bleeding (increases the effects of Coumadin)


Myxedema Coma

Sudden drop in thyroid hormone
Due to undiagnosed or untreated hypothyroidism or incorrect treatment (inadequate dose, pt stops taking his/her medications suddenly)
Or precipitated by: trauma, infection, or surgery
Rare but often deadly
Risk Factors: new-onset HF, recent stroke, use of amiodarone, lithium, phenothiazines, tranquilizers


Myxedema Coma: S & S

Exaggerated hypothyroidism S & S
 Weakness
 Confusion (untreated, leads to coma)
 Hypothermia (severe)
 Edema
 Breathing difficulties
 Most common in older women in winter months
 **mental status and respiratory assessment a priority


Myxedema Coma: Treatment

Administer oxygen
Ventilator support
Levothyroxine IV initially


Nursing Diagnoses

Ineffective breathing pattern related to decreased energy, weight gain and fatigue
Decreased cardiac output related to altered heart rate and rhythm
Disturbed thought processes related to impaired brain metabolism and edema


Treatment: Hyperthyroidism

 More complicated than hypothyroidism
 Managed by an endocrinologist

Treatment Options:
 Radioactive Iodine therapy (RAI) (treatment of choice)
 Antithyroid medications
 Iodine products
 Surgery
 Beta-blockers


Radioactive Iodine Therapy

 Oral doses are absorbed quickly by the stomach and intestines, then carried in the bloodstream to the thyroid, where it is taken up by the gland.
 Radioactive iodine only affects the thyroid gland. Thyroid cells are the main target in the body that can absorb iodine, so there is very little radiation exposure to the rest of the body's cells.
 While in the thyroid gland, the RAI disrupts the function of some of the thyroid cells - the more radioactive iodine given, the more cells cease to function.
 As the cells stop functioning, excessive amounts of thyroid hormones are no longer produced, and symptoms of hyperthyroidism begin to disappear with the risk of hypothyroidism. (It might seem odd to replace one disorder with another, but hypothyroidism is much easier to treat on a long-term basis than hyperthyroidism. )



• Concentrates in thyroid and destroys tissue
• Patients eventually develop hypothyroidism and need thyroid replacement therapy
• Effectiveness monitored q 4-6 weeks
• RAI is shed in stool, urine, saliva -precaution is necessary
• Avoid body fluid contact with others for 48-72 hours after treatment
• Double flush toilet
• Contraindicated with:
o Pregnancy (delay until 6 months post-treatment)
o Breastfeeding


Radioactive Iodine Uptake Test –=

measures absorption by the thyroid gland (calculated dose given (po or IV), thyroid is scanned in 24hr of distribution of RAI
The iodine is concentrated in the thyroid gland
The dose of radiation with these tests is very small and has no major side effects to the patient
Special precaution when nursing these patients – isolation rooms, avoid contact with body fluids
RAI is excreted in the urine, stool and saliva


A Special Caution for Women 

Pregnant women or women who want to become pregnant in the next 6 months should not use radioactive iodine, as the treatment can destroy the fetus's thyroid and impair its development.
Women should wait a year before conceiving if they have been treated with the therapy.
Women who are breast-feeding should also not use radioactive iodine.



Propylthiouracil (PTU) and methimazole
For mild disease or contraindications to RAI
Used in hyperthyroidism to prevent the surge of thyroid hormones that occurs after surgical treatment or during radioactive iodine treatment
Given over 12-18 months
Risk of relapse
Patients assessed every 3 months
Side effects - May cause liver and bone marrow toxicity


Iodine Therapy

Inhibits thyroid hormone release
Rapid onset
Often used to treat thyrotoxicosis or thyroid storm
Adjunct therapy for RAI
Can be used prior to surgery
Eg: potassium idodide
Effects last only a few weeks



• Removal of entire thyroid gland or subtotal thyroidectomy
• Risk of complications
o Hemorrhage, laryngeal edema, vocal cord paralysis
• Used when RAI contraindicated or patient preference
o Pregnant or planning to be in next 6 months


Post surgery: Hypothyroidism -

This more often occurs when the entire thyroid is removed, but it can still happen when only part of the thyroid is removed.

To compensate for the lack of thyroid hormones, the patient will take thyroid replacement therapy for life



the body may be more prone to a temporary period of hypocalcemia that responds well to oral calcium supplements with full recovery.

Occurs because hyperthyroidism can deplete the body of its normal calcium stores before surgery, and it takes some time to replenish this after surgery



• Adjunctive therapy
• Patients with atrial fibrillation with rapid ventricular response
• May also reduce :
o Body temperature
o Diaphoresis
o Tremors
o Palpitations
o Anxiety


Graves’s Eye Disease

• Findings only seen with hyperthryoidism caused by Graves’ disease
• Exophthalmos
o Wide-eyed, startled look
o Lid retraction
o Globe and lid lag
o May have impaired vision
o Dry eyes (lid cannot close)-risk for corneal abrasion, infection
o Redness, tearing, bloodshot, photophobia



• Treatment for hyperthyroidism does not improve the eye and vision problems
• Treatment is symptomatic
• Elevate the head at night
• Eye lubricant
• Dark Glasses for photophobia
• Steroids or Diuretics may be used


Thyroid Storm

• Due to too much thyroid hormone (induced by stress, infection, too high dose of thyroid medication or overdose of thyroid medication)
• Exaggerated hyperthyroidism S & S
• Mainly due to increased metabolic rate and oxygen demands
• Extreme temperature (40.7 C)**cardinal sign
• Severe tachycardia
• Cardiac dysrrhythmia, HF and shock
• Restless, agitation, seizures
• N & V & D
• Weakness & confusion or disorientation


Thyroid Storm: Treatment

Continuous cardiac monitoring
Supplemental oxygen
IV access for fluid resuscitation
Risk of hypovolemic shock
Monitor intake and output to ensure accurate fluid replacement
Administer PTU or methimazole and iodine
Ice packs & cooling blankets
Monitor cardiac rhythm, VS, I & O


Hyperthyroid: Nursing Assessment and Management

• Assess apical pulse, BP and temperature q 4h
• Teach patient to report palpitations, dyspnea, vertigo, chest pain
• Immediately report temperature increase of 0.6°C
o (ie: 37°C increases to 37.6° C)
• Assess cardiac status
• Reduce stimulation
• Promote comfort
• Administer meds as ordered


Nursing Diagnoses: Hyperthyroidism

• Imbalanced nutrition: less than body requirements
• Hyperthermia related to increased metabolic rate
• Fatigue related to sleep deprivation
• Potential for hypertension and cardiac failure


Thyroid Disorders: Nursing Considerations

• Ensure patient aware of long term nature of therapy and follow up, especially with changes to health status
• Teach S &S of hypo and hyperthyroidism
• Monitor TSH level every 6-8 weeks until normal
• Monitor TSH annually thereafter or if S & S reported
• TSH level normal range 0.5 to 5 mU/L
• Teach S & S of complications & when to call 911
• Monitor/assess for:
o Anemia, hyperlipidemia, depression, menstrual changes, abnormal BP, electrolyte disturbances, blood glucose changes