Medication Summary
Possible medical therapy includes antithyroid medications, thyroid hormone replacement, and radioiodine ablation. Antithyroid therapy is used to physiologically stabilize the patient before surgical excision of a toxic nodule. Thyroid hormones are necessary postoperatively after thyroidectomy for replacement and suppression of thyroid-stimulating hormone (TSH). Radioiodine ablation may be employed to treat the presence of residual disease and sometimes for suppression of a toxic nodule. Its use requires the cooperation of an experienced specialist. In addition, calcium supplementation may be required in the case of parathyroid complications, whether temporarily or permanently.
Thyroid hormones
Class Summary
Replacement is indicated after thyroidectomy to maintain levels and to prevent TSH stimulation of any remaining cells.
Levothyroxine (Levothroid, Levoxyl, Synthroid, Unithroid)
DOC. Levothyroxine exerts its effect largely after it is deiodinated to tri-iodothyronine at its site of action. In active form, influences growth and maturation of tissues. Involved in normal growth, metabolism, and development.
Liothyronine (Cytomel)
Synthetic form of natural thyroid hormone T3 converted from T4. Duration of activity is short and allows for quick dosage adjustments in event of overdosage. Active form influences growth and maturation of tissues.
Antithyroid agents
Class Summary
These agents are used when treating hot nodules before surgery.
Methimazole (Tapazole)
Inhibits thyroid hormone by blocking oxidation of iodine in thyroid gland. However, it does not inhibit peripheral conversion of thyroid hormone. Gradually taper to minimum dose required to clinically maintain euthyroidism. Caution during pregnancy because it can cause fetal hypothyroidism and has been associated with fetal aplasia cutis.
Propylthiouracil (PTU)
Derivative of thiourea that inhibits organification of iodine by thyroid gland. Blocks oxidation of iodine in thyroid gland, thereby inhibiting thyroid hormone synthesis; inhibits conversion of T4 to T3 (an advantage over other agents). DOC in pregnancy-associated thyrotoxicosis but should be used in lowest effective dose because of risk of hypothyroidism to fetus.
Beta-adrenergic receptor blocking agents
Class Summary
These agents are used to control symptoms from hyperthyroidism. Inhibit chronotropic, inotropic, and vasodilatory responses to beta-adrenergic stimulation.
Propranolol (Inderal)
DOC in treating cardiac arrhythmias resulting from hyperthyroidism. Controls cardiac and psychomotor manifestations within minutes.
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A 12-year-old patient with an asymptomatic palpable thyroid nodule noticed upon routine physical examination.
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Surgical specimen of a thyroid lobe with papillary carcinoma taken from a 12-year-old patient with an asymptomatic palpable thyroid nodule noticed upon routine physical examination.
