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Chapter 34
Agents Affecting Thyroid, Parathyroid, and Pituitary Function
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Agents Affecting Thyroid, Parathyroid, and Pituitary Function Goal: maintenance of physiologic
stability Hypothalamus and the pituitary gland
Form the neuroendocrine system Main director is the hypothalamus
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Pituitary Gland Adenohypophysis (anterior pituitary) Neurohypophysis (posterior pituitary)
Linked to the hypothalamus Pituitary gland secretes hormones Coordinates action of other endocrine
glands Influences growth and development of the
body
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Pituitary Disorders
Hypopituitarism Underproduction of pituitary
hormones Therapy
Corticosteroids: a life and death issue Thyroid replacement Sex hormone replacement
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Pituitary Disorders Hyperpituitarism
Overproduction of pituitary hormones Signs and symptoms: gigantism and
acromegaly Treatment
Chemotherapy Radiation Surgery—inactivation or removal
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Pituitary Disorders Diabetes insipidus
Caused by a deficiency or total absence of vasopressin (ADH)
Signs and symptoms Huge urine output (polyuria) Increased thirst (polydipsia) Hypernatremia (increased sodium) Dehydration
Treatment: antidiuretic hormone
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Antidiuretic Hormone (ADH)
Directs the body to retain water and sodium Focus is on water versus sodium
Causes vasoconstriction Synthetic ADH drugs
Lypressin Vasopressin
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Nursing Considerations Monitor: weight, I&O, vasopressin
toxicity, B/P daily Vasopressin: regular schedule Teach: may produce chest pain;
administration techniques Watch the elderly and patients with
CAD carefully
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Thyroid Gland
Thyroid gland location: neckProduces T3 and T4 hormones
Cellular metabolismProduces calcitonin
Inhibits bone resorption
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Thyroid
Maintains metabolic rate Two thyroid hormones Synthesis is a series of chemical steps Synthesis is dependent on thyroid
stimulating hormone (TSH) Negative feedback system Thyroid hormone increases – TSH is
suppressed
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Thyroid Hormones
Regulate lipid and carbohydrate metabolism
Essential for normal growth and development
Affect heat production in the body
Thyroid Hormones
(cont’d) Promotes metabolic breakdown of
cholesterol to bile acids Accelerates utilization of
carbohydrates Dysfunction has serious
consequences
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Thyroid Disorders: Hyperthyroidism Excessive secretion of thyroid
hormones Increased metabolism
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Hyperthyroidism: S/S Skin hot and dry Increased cardiac and respiratory rates Weight loss Increased appetite Muscle weakness Nervousness Irritability Unable to sleep well
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Antithyroid Drugs
Inhibits coupling of iodine Prevent T3 and T4 formation
Iodides Stop thyrotropin from being active
Inhibits the production of T3 and T4 Radioactive isotopes
Diagnose and treat hyperthyroidism Radiation destroys the thyroid gland
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Antithyroid Drugs Methimazole and propylthiouracil (PTU) Side effects/adverse effects
Liver and bone marrow toxicity Interactions
Increased activity of oral anticoagulants Additive agranulocytosis when taken with
bone marrow depressants Therapeutic results
Normal metabolic rate
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Iodides
Treats mild cases of hyperthyroidism Inhibits production of thyroid
hormones May have effect in 24 hours Maximum effect with 10-15 days Thyroid gland may “escape” from
iodine inhibition
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Sodium Iodide I 131 Radioactive isotopes of iodine Used for diagnosis and treatment of
hyperthyroidism Oral or IV Taken up by the thyroid gland Destructive radiation destroys thyroid cells Careful dose selection limits amount of
damage
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Beta-Adrenergic Blocking Agents Suppresses signs and symptoms of hyperthyroidism
- tachycardia
- tremor
- anxiety Do not inhibit function of the thyroid gland An adjunct to other forms of therapy
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Surgery
Subtotal thyroidectomy Used when other forms of therapy are
contraindicated
- pregnancy
- young children Thyroid function is brought to normal
function prior to surgery (euthyroid state) with thyroid suppression agents
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Nursing Considerations: hyperthyroid Assess activity level, food intake, body
weight Dilute liquid iodine medications Watch for iodism, thyroid storm Patients who have had I131 should avoid
children and pregnant women for one week
Watch for symptoms of hypothyroidism
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Thyroid Disorders: Hypothyroidism Decreased secretion of thyroid hormones
Decreased metabolism
Clinical signs and symptoms Thickened skin Decreased cardiac and respiratory rates Weight gain Loss of appetite, anorexia Muscle weakness Lethargy
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Hypothyroidism
Nongoitrous Goitrous
- enlarged thyroid glands caused by excessive
stimulation of TSH Causes many symptoms Cretinism in an infant is the result of
absence or atrophy of the thyroid during fetal life
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Hypothyroidism Called cretinism in children
Underdeveloped growth rate Low metabolic rate Mental retardation
Called myxedema in adults Low metabolic rate Loss of mental and physical stamina Hair loss, firm edema
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Hypothyroidism
Goal is to replace the thyroid hormoneLevothyroxine sodium
(Synthroid) Widely prescribed synthetic
thyroid hormone
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Hypothyroidism Thyroid (levothyroxine sodium) preparations Cause interactions
Oral anticoagulants: increased anticoagulant effect Digitalis: decreased serum levels Hypoglycemic agents: decreased effect
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Nursing Considerations
Assess activity tolerance, food intake, body weight, sleep pattern
Take apical pulse for one minute Withhold when heart rate greater than 100 Administer before breakfast Observe for effectiveness of treatment Report toxic signs and symptoms
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Client Teaching Tips
General client teaching tips for clients with thyroid disorders Too high of a dose will result in
nervousness, irritability, and insomnia Keep a log of pulse, weight, and mood
status Avoid foods high in iodine such as soy,
tofu, turnips, seafood, and iodized salt
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Client Teaching Tips
Immediately report chest pain. Synthroid takes several weeks to
months to reach the therapeutic level.
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Parathyroid Glands
Parathyroid Pinhead-sized structures located on
either side of the thyroid gland Primary function
Parathormone secretion It promotes bone resorption
(breakdown of the bone)
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Parathyroid
When calcium increases, PTH decreases and calcitonin is released
Calcitonin reduces serum calcium levels
All helps to regulate serum calcium levels
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Hypoparathyroidism
Parathormone deficiency Result
Decreased blood levels of calcium Increased phosphate levels Neuromuscular irritability Psychiatric disorders
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Treatment of Hypoparathyroidism Replenishment of calcium stores During acute stage IV administration
of calcium salts Maintenance with oral therapy Vitamin D is also administered to
promote absorption of calcium from the GI tract
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Hyperparathyroidism Oversecretion of parathormone Result
Increased blood levels of calcium Decreased phosphate levels Kidney stones
Treatment Replace the calcitonin Replace the phosphate
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Treatment of Hyperparathyroidism Often includes surgery Phosphate supplementation Lasix may be given to promote
calcium excretion
Treatment of Hyperparathyroidism(cont’d)
Calcitonin administration Administered subcutaneously or
IM Other agents as outlined in book
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Nursing Considerations
Assess patient for fatigue, muscle weakness, and other symptoms
Calcium preparations should be warmed to body temperature prior to IV administration
Nursing Considerations
ECG monitoring during calcium administration
Patient to remain in bed
Oral calcium should not be given with food
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