Drugs Used to Treat Thyroid Disease Chapter 37 Drugs Used to Treat Thyroid Disease Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Chapter 37 Lesson 37.1 Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives Describe the function of the thyroid gland Describe the signs, symptoms, treatment, and nursing interventions associated with hypothyroidism and hyperthyroidism State the three types of treatment for hyperthyroidism Identify the two classes of drugs used to treat thyroid disease Explain the nutritional requirements and activity restrictions needed for an individual with hyperthyroidism State the drug of choice for hypothyroidism Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Objectives (cont’d) Cite the actions of antithyroid medications on the formation and release of the hormones produced by the thyroid gland Identify the types of conditions that respond favorably to the use of radioactive iodine-131 Cite the action of propylthiouracil on the synthesis of triiodothyronine and thyroxine Explain the effects of hyperthyroidism on doses of warfarin and digoxin and on those taking oral hypoglycemic agents Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Thyroid Functions Hypothalamus secretes thyrotropin-releasing hormone (TRH) Anterior pituitary secretes thyroid-stimulating hormone (TSH) in response to TRH Thyroid gland secretes T3 and T4 in response to TSH T3 and T4 regulate: General body metabolism Carbohydrate, protein, lipid metabolism Thermal regulation Cardiovascular function Growth and maturation Lactation and reproduction Thyroid function is regulated by the hypothalamus and the anterior pituitary gland. Synthesis of thyroid hormones depends on sufficient iodine intake through food and water. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Thyroid Disorders Hypothyroidism: inadequate thyroid hormones Myxedema: occurs during adult life Cretinism: born without a thyroid gland, or hypoactive one Hyperthyroidism: excess production of thyroid hormones Diseases causing overproduction: Graves’ disease, nodular goiter, thyroiditis, thyroid carcinoma, tumors of the pituitary gland Overdose of thyroid hormones Thyrotoxicosis: also known as hyperthyroidism Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Treatment of Thyroid Disease Goal of therapy Return to a normal thyroid state Two classes of drugs Thyroid replacement hormones (hypothyroid) Antithyroid agents (hyperthyroid) Hyperthyroidism – three treatments used Subtotal thyroidectomy Radioactive iodine Antithyroid medications May be 1 to 3 weeks after drug initiation that the drug’s effects are noticed. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Nursing Interventions for Thyroid Disorders Hypothyroidism History of prior treatment for thyroid disorders, cardiac disease, or adrenal insufficiency Request list of medications being taken Perform focused assessment of body systems Nutritional requirements (low-calorie diet) Activity restrictions Hyperthyroidism Nutritional requirements (high-calorie diet) Not all systems may be affected. Nursing care, diagnosis, and treatment focuses on affected systems. Encourage moderate exercise as tolerated, focusing on safety during ambulation if muscle weakness, wasting, or discomfort is present. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Drug Class: Thyroid Replacement Hormones Actions Replace deficient T3 and T4 hormones Uses Return patient to normal thyroid state Common and serious adverse effects Signs of hyperthyroidism; hyperglycemia Drug interactions Warfarin, digoxin, estrogens, cholestyramine For specific drugs, see Table 37-1. Levothyroxine is the most commonly used medication. Patients taking oral hypoglycemic agents or insulin may require adjustment. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Drug Class: Antithyroid Medicines Drug: iodine-131 (131I) Actions Selectively destroy hyperactive thyroid tissue Uses Treat hyperthyroidism for select individuals Common and serious adverse effects Tenderness in the thyroid gland; hyperthyroidism; hypothyroidism Drug interactions Lithium carbonate Used primarily for certain patients who may not be candidates for more aggressive treatment. Iodine-131 is a radioactive isotope of iodine that is absorbed into the thyroid gland in high concentrations. 3 to 6 months for full benefit to be seen. Extremely dangerous; wear latex gloves, watch for personnel who have allergies, follow hospital policy for spills. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.

Drug Class: Antithyroid Medicines (cont’d) Drugs Propylthiouracil (PTU, Propacil) Methimazole (Tapazole) Actions Block synthesis of T3 and T4 Uses Long-term treatment for hyperthyroidism Presurgical treatment Common and serious adverse effects Purpuric, maculopapular rash; headache; nephrotoxicity; hepatotoxicity; bone marrow suppression, lymph node enlargement Will not destroy T3 and T4 already produced; few days to 3 weeks before symptoms improve. Drug interactions: warfarin dosage may have to be increased; digoxin dosage may have to be decreased. Mosby items and derived items © 2010, 2007, 2004 by Mosby, Inc., an affiliate of Elsevier Inc.