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3 Primary thyroid hormones
and their actions.
- T3 ~Triiodothyronine
- T4~ Thyroxine
- Thyrocalcitonin
- Actions:
- Controls metabolic rate of all cells
- Regulates protein, carbohydrate and fat metabolism
- Increase red blood cell formation
- Affects growth and development of all cells
- Acts as an insulin antagonist
- Increases bone formation and resorption
- Cand be thought of as a check/balance for the pancreas.
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Four Steps of Thyroid hormone synthesis.
- Active transport of iodide into thyroid
- Oxidation of iodide into iodine
- Iodine incorporated into thyrosine
- Thyroid hormones released by proteolytic enzymes
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Thyroid Function Test
- Serum T4 Test: Measures total thyroxine; for screening and monitoring replacement therapy
- Serum T3 Test: Measures total Triiodothyronine; Tests for hyperthyroidism and monitoring therapy
- Serum TSH: Most sensitive method for diagnosing hypothyroidism
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Terms for hypothyroidism
- Mild deficiency: Hypothyroidism
- Severe Deficiency: Myxedema
- Cretinism: Hypothyroidism in infants
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Hypothyroid SnSs
- Face: Pale, puffy and expressionless
- Skin: Cold and dry
- Hair: brittle
- HR and T: lowered
- Lethargy and fatigue
- Intolerance to cold
- Slowed mentality
- Enlarged thyroid
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Causes of Hypothyroidism
- Autoimmune thyroiditis (Hashimoto’s Disease)
- Surgical removal of thyroid
- Destruction of thyroid by radioactive iodine
- Insufficient secretion of TSH and TRH
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Levothryroxine (T3)
Synthroid
- Converts to T4
- Highly protein bound (eat on empty stomach)
- Half-life 7 days
- Adverse effects:
- Tachycardia: might be getting too much
- Angina: might be getting too much
- Tremors: might be getting too much
- Nursing Implications
- Teach pt that Rx will not get to therapeutic level for ~ 1 month.
- Check apical pulse prior to administration
- Withhold if pulse above 100
- Report chest pain
- Administer early in am to prevent insomnia
- Caffeine will also inhibit absorption.
- Don't want to take generic equivilant if you've already started with name brand.
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Hyperthyroid general info
- AKA Graves Disease: Most Common, especially in females
- Toxic Nodular Goiter (Plummer’s Disease): Result of Thyroid adenoma
- Thyrotoxic Crisis (Thyroid Storm): Occurs when thyroid hormone levels are extremely high
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SnSs of Hyperthyroid
- HR: strong and rapid with possible dysrhythmias, angina, and tachycardia.
- CNS effects
- --Rapid speech
- --Nervousness
- --Insomnia
- Exophthalmos (bug-eyed): good teaching point.
- Muscle weakness and atrophy
- Metabolic rate is raised with increased T4
- Intolerance to heat
- Warm, moist skin
- Increased appetite with weight loss
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Propylthiouracil (PTU)
- Inhibits thyroid hormone synthesis
- Short half-life
- Adverse Effects
- --Agranulocytosis: destruction of wbcs (Within first 2 months of therapy)
- --Hypothyroidism (Occurs with excessive dosing)
- Neonatal hypothyroidism
- --Crosses the placenta
- --Enters breast milk
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Radioactive Iodine I 131
- Most typical treatment
- Radioactive isotope
- Emits gamma and beta rays--> destruction of thyroid tissue.
- Half-life 8 days
- Candidates Generally not for those under 30 years of age
- Action
- Produces clinical remission with destruction of thyroid gland
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Thyrotoxic Crisis
- Occurs with extreme levels of thyroid hormone
- Symptoms
- Hyperthermia (105 or higher! Will occure immediately postop. Take full set of vitals!)
- Severe tachycardia
- Profound weakness
- Unconsciousness
- Heart failure
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Treatment of Thyroid Crisis
- Propylthiouracil
- Suppress synthesis and conversion of T4 to T3
- Propranolol (beta blocker--> decreased HR)
- High doses of Potassium iodide
- Sedation
- Cooling
- Glucocorticoids
- IVF’s
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