Chapter 35

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

Consists of: Adenohypophysis (anterior pituitary) Neurohypophysis (posterior pituitary)

Linked to the hypothalamus Pituitary gland secretes hormones

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Hormones secreted by the anterior pituitary

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Pituitary and Thyroid Glands

Pituitary gland Thyroid-stimulating hormone (TSH)

Thyroid gland location: neck Produces T3 and T4 hormones

Cellular metabolism

Produces calcitonin Inhibits bone resorption

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Thyroid Disorders

Hyperthyroidism Hypothyroidism

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Hyperthyroidism

Excessive secretion of thyroid hormones

Increased metabolism

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Hyperthyroidism

Clinical signs and symptoms 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 propyithiouracil (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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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

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 hormone Levothyroxine 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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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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Hypoparathyroidism

Parathormone deficiency Result

Decreased blood levels of calcium Increased phosphate levels Neuromuscular irritability Psychiatric disorders

Treatment Replace the calcium

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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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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