chapter 34 agents affecting thyroid, parathyroid, and pituitary function

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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