Thyroid Disorders and Treatments

• Thyroid disorders involve imbalances in thyroid hormone production, treated with thyroid and anti-thyroid drugs.

Thyroid Gland

• The thyroid gland secretes three hormones that are essential for metabolism regulation: thyroxine (T4), triiodothyronine (T3), and calcitonin.
• Calcitonin helps build T3 and T4.
• Iodine is needed to convert T4 to T3.
• The thyroid gland is located near the parathyroid gland which keeps the levels of calcium in the extracellular fluid adequate.

Hypothyroidism Etiology and Pathophysiology

• Hypothyroidism can be primary, secondary, or tertiary.
• Primary hypothyroidism is typically a gland issue and the most common, related to the destruction of thyroid tissue or defective hormone synthesis.
• Hormone findings include decreased T3 (triiodothyronine) and T4 (thyroxine) levels, and increased thyroid-stimulating hormone (TSH) levels.
• Secondary hypothyroidism is rare and related to pituitary disease (tumor) with decreased TSH secretion.
• Tertiary hypothyroidism involves a reduced level of thyrotropin-releasing hormone (TRH) from the hypothalamus.

Disorders of Thyroid Gland

• Thyroid gland disorders, from hyper to hypo include thyroid storm, hyperthyroidism, euthyroid, hypothyroidism, and myxedema coma.

Hypothyroidism: Transient and Congenital

• Hypothyroidism may be transient, related to thyroiditis or discontinuing thyroid hormone therapy.
• Congenital hypothyroidism involves hyposecretion of thyroid hormone during youth, leading to a low metabolic rate, retarded growth, and slowed mental development.

Hypothyroidism: Myxedema

• Myxedema is the hyposecretion of thyroid hormone during adulthood, leading to decreased metabolic rate, loss of mental and physical stamina, weight gain, loss of hair, firm edema, and yellow dullness of the skin.

Hypothyroidism: Goiter

• Goiter is an enlargement of the thyroid gland resulting from overstimulation by elevated levels of TSH.
• TSH is elevated because there is little to no thyroid hormone in circulation.

Goiter Process and Feedback

• Normal negative feedback involves the hypothalamus releasing TRH, the pituitary releasing TSH, and the thyroid gland releasing T3 and T4; when levels are adequate, TRH and TSH release is turned off.
• In the goiter process, the hypothalamus releases TRH, the pituitary releases TSH, but the thyroid gland does not produce T4 and T3; there is no message to stop TRH and TSH, resulting from overstimulation by elevated levels of TSH.

Hypothyroidism Contributing Factors

• Iodine deficiency, where iodine is neded to convert T4 to T3, is the most common cause of hypothyroidism worldwide, prevalent in iodine-deficient areas.
• Atrophy of the gland is the primary cause of hypothyroidism in locations where iodine intake is adequate.
• Hypothyroidism may also develop because of treatment for hyperthyroidism (Graves' disease), where treatment essentially kills the gland, requiring lifelong thyroid replacements.
• Amiodarone and lithium can cause hypothyroidism.

Hypothyroidism Manifestations

• Hypothyroidism's clinical manifestations vary depending on severity, duration, and age of onset.
• It results in systemic effects characterized by the slowing of body processes.
• Ranges from no symptoms to classic symptoms and physical changes easily detected on examination.
• The onset of symptoms may occur over months to years, unless it occurs after thyroidectomy, thyroid ablation, or treatment with antithyroid drugs.

Hypothyroidism Complications: Myxedema Coma

• Myxedema coma involves mental sluggishness and drowsiness, leading the to lethargy that progressing gradually to impairment of consciousness or coma.
• It is precipitated by infection, drugs (especially opioids, tranquilizers, & barbiturates), exposure to cold, or trauma.
• Characterized by subnormal temperature, hypotension, and hypoventilation.
• To survive, the patient's vital functions must be supported, and IV thyroid hormone replacement must be administered.

Thyroid Replacement Drug Therapy: Mechanism of Action

• Levothyroxine is a synthetic thyroid hormone T4.
• Liothyronine is a synthetic thyroid hormone T3.
• Liotrix is a synthetic thyroid hormone T3 and T4 combined.
• Oral administration should occur 1/2 hour to 1 hour before breakfast to facilitate absorption.
• Thyroid hormones are a synthetic form of thyroxine (T4), liothyronine (T3), or a combination of T3 and T4 which increase metabolic rate, protein synthesis, cardiac output, renal perfusion, oxygen use, body temperature, blood volume and growth process.
• Thyroid preparations replace what the thyroid gland cannot produce to achieve normal thyroid levels (euthyroid).

Thyroid Replacement: Indications

• Thyroid drugs are used to treat all three forms of hypothyroidism.
• Levothyroxine is the preferred drug because its hormonal content is standardized; therefore, its effect is predictable.
• Thyroid medications are also used for thyroid replacement in patients whose thyroid glands have been surgically removed or destroyed by radioactive iodine in the treatment of thyroid cancer or hyperthyroidism.
• Used for emergency treatment of myxedema coma and treat Hypothyroidism in pregnancy.

Thyroid Drug Therapy: Adverse Effects

• Cardiac dysrhythmia is the most significant adverse effect of thyroid medication.
• Other adverse effects include tachycardia, palpitations, angina, hypertension, insomnia, tremors, headache, heat intolerance, sweating, appetite changes, weight loss due to increased metabolism, menstrual irregularities, diarrhea, nausea, and anxiety.
• All medications can result in hyperthyroidism.

Thyroid Replacement: Contraindications and Interactions

• Thyroid medications are contraindicated for obesity treatment and following a myocardial infarction (MI) due to cardiac stimulation.
• Interactions can occur with binding agents, cholestyramine, antacids, antiseizure medications, and anticoagulants.

Nursing Implications

• Assess for drug allergies, contraindications, and potential drug interactions.
• Obtain baseline vital signs and weight.
• Use thyroid medication cautiously for those with cardiac disease, hypertension, and pregnant women.
• During pregnancy, treatment for hypothyroidism should continue.
• Fetal growth may be retarded if maternal hypothyroidism is untreated during pregnancy.
• Adjust dosage every 4 weeks to keep TSH at the lower end of the normal range.
• Teach patient to take thyroid drugs once daily in the morning to decrease the likelihood of insomnia; take medications at the same time every day and not to switch brands without physician approval; report any unusual symptoms, chest pain, or heart palpitations; not to take over-the-counter medications without physician approval; and that therapeutic effects may take several months to occur.
• Teach patients the importance of alerting health care providers of thyroid medication use, may enhance activity of anticoagulants (stimulation of glucose), diabetic patients may need increased dosages of hypoglycemic meds, and may decrease serum digoxin levels.

Hyperthyroidism: Causes

• Hyperthyroidism causes include Graves' disease (autoimmune disease), multinodular disease, Plummer's disease (also called toxic nodular disease), and thyroid storm (induced by stress or infection, severe and potentially life-threatening).

Hyperthyroidism

• An increased level of thyroid hormone increases the metabolic rate.

Hyperthyroidism Etiology and Pathophysiology

• Hyperthyroidism is a sustained increase in the synthesis and release of thyroid hormones by the thyroid gland.
• It often occurs more often in women and highest frequency in 20-40 yrs.
• Thyrotoxicosis involves physiologic effects/clinical syndrome of hypermetabolism resulting from increased circulating levels of T3 and/or T4.
• Hyperthyroidism and thyrotoxicosis occur together as Graves' disease.

Hyperthyroidism: Graves Disease Etiology and Pathophysiology

• Graves' disease is an autoimmune disease of unknown origin, with diffuse thyroid enlargement and excessive thyroid hormone secretion (T3 and T4).
• Antibodies are developed to the TSH receptor, which leads to clinical manifestations of thyrotoxicosis and may progress to destruction of thyroid tissue resulting in hypothyroidism.
• Precipitating factors include insufficient iodine supply, infections, and stressful life events interacting with genetic factors accounting for 75% of cases of hyperthyroidism.

Hyperthyroidism: Clinical Manifestations

• Hyperthyroidisms clinical manifestations are related to the effect of thyroid hormone excess causing increased metabolism and tissue sensitivity to stimulation by the sympathetic nervous system.
• It results in intolerance to heat, increased sensitivity to stimulant drugs, and an elevated basal temperature.

Hyperthyroidism: Complications

• Thyrotoxic crisis involves excess amounts of thyroid hormones and is an acute, rare condition, where all manifestations are heightened.
• It is a life-threatening emergency, but death is rare when treatment is initiated
• Presumed causes are additional stressors.

Thyrotoxic Crisis

• Manifestations of thyrotoxic crisis include tachycardia, heart failure, shock, hyperthermia, restlessness, agitation, seizures, abdominal pain, nausea, vomiting, diarrhea, delirium, and coma.
• Treatment goal: Decrease thyroid hormone levels and clinical manifestations with drug therapy.
• Therapy should be aimed at managing respiratory distress, fever reduction, fluid replacement, and management of stressors.

Treatment of Hyperthyroidism

• Treatment includes radioactive iodine which destroys the thyroid gland resulting in hypothyroidism and the need for lifelong thyroid hormone replacement.
• Surgery to remove all or part of the thyroid gland will require lifelong thyroid hormone replacement.
• Anti-thyroid drugs include thioamide derivatives and beta-blockers for symptom management only, blocking the sympathetic response.

Antithyroid Drugs

• Antithyroid drugs include methimazole and propylthiouracil (PTU).
• Mechanism of Action is to inhibit the incorporation of iodine molecules into the amino acid tyrosine, which is required to make T3 and T4.
• Therapeutic uses include Graves' disease, to produce a euthyroid state prior to removing the thyroid and as an adjunct to the irradiation of the thyroid gland; and for emergency treatment of thyrotoxicosis.

Anti-thyroid Drugs Nursing Considerations

• Adverse effects can include a decrease in the body's ability to fight infections as well as liver and bone marrow toxicity.
• Over medication can result in symptoms of hypothyroidism.
• The drug is contraindicated in those with a drug allergy.
• Nursing considerations: it will take 1-2 weeks before improvements can be seen.
• It is important to monitor vital signs, I&O, and weights; give the medication at a consistent time each day with meals, and the medication should not be discontinued abruptly.
• Monitor for indications of hypothyroidism and CBC, a beta-blocker may be given to decrease tremors and tachycardia.

SDOH

• Levothyroxine (90 tablets) - $56.
• with PTU - $100 without insurance, $18 with insurance
• – Methimazole (90 tablets) - $20 with insurance.