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  • Image not available. Advances in the understanding of the structure and metabolism of thyroid hormones, and the molecular biology of thyroid hormone receptors have provided insight into the various abnormalities that give rise to hyperthyroidism and hypothyroidism.
  • Image not available. Thyrotoxicosis is most commonly caused by Graves’ disease, which is an autoimmune disorder in which thyroid-stimulating antibody (TSAb) directed against the thyrotropin receptor elicits the same biologic response as thyroid-stimulating hormone (TSH).
  • Image not available. Hyperthyroidism may be treated with antithyroid drugs such as methimazole (MMI) or propylthiouracil (PTU), radioactive iodine (RAI: sodium iodide-131 [131I]), or surgical removal of the thyroid gland; selection of the initial treatment approach is based on patient characteristics such as age, concurrent physiology (e.g., pregnancy), comorbidities (e.g., chronic obstructive lung disease), and convenience.
  • Image not available. MMI and PTU reduce the synthesis of thyroid hormones and are similar in efficacy and overall adverse effects, but their dosing ranges differ by 10-fold.
  • Image not available. Response to MMI and PTU is seen in 4 to 6 weeks with a maximal response in 4 to 6 months; treatment usually continues for 1 to 2 years, and therapy is monitored by clinical signs and symptoms and by measuring the serum concentrations of TSH and free thyroxine (T4).
  • Image not available. Subclinical hyperthyroidism is associated with cardiovascular mortality, especially in the elderly in whom treatment is recommended.
  • Image not available. Adjunctive therapy with β-blockers controls the adrenergic symptoms of thyrotoxicosis but does not correct the underlying disorder; iodine may also be used adjunctively in preparation for surgery and acutely for thyroid storm.
  • Image not available. Many patients choose to have ablative therapy with 131I rather than undergo repeated courses of MMI or PTU treatment; most patients receiving RAI eventually become hypothyroid and require thyroid hormone supplementation.
  • Image not available. Hypothyroidism is most often due to an autoimmune disorder known as Hashimoto’s thyroiditis.
  • Image not available. The drug of choice for replacement therapy in hypothyroidism is levothyroxine.
  • Image not available. Studies of combination therapy with levothyroxine and triiodothyronine have not shown reproducible benefits. This approach to treatment of hypothyroidism requires further study.
  • Image not available. Monitoring of levothyroxine replacement therapy is achieved by observing clinical signs and symptoms and by measuring the serum TSH. An elevated TSH indicates underreplacement; a suppressed TSH indicates overreplacement.
  • Image not available. There is controversy about the treatment of mild (subclinical) hypothyroidism. Generally, benefits of treatment are clearest in younger populations.
  • Image not available. Despite the simplicity of the concept of correction of hypothyroidism with levothyroxine, many treated patients have iatrogenic hyperthyroidism or are underreplaced.
  • Image not available. Hypothyroidism during pregnancy should be treated to achieve TSH values that are normal, based on reference ranges for TSH derived from the pregnant population.

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  1. Describe the signs and symptoms of hyperthyroidism and hypothyroidism.

  2. Outline the changes seen in thyroid function tests (TSH, free and total T4 and T3) in hyperthyroidism and hypothyroidism, and the radioactive iodine uptake (RAIU) scan in hyperthyroidism.

  3. Describe the mode of action, patient selection, maintenance and maximal doses, drug interactions, and adverse effects for thionamides, radioactive iodine (RAI), β-blockers, and iodides.

  4. Outline the treatment for thyroid storm ...

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