Thyroid LOs

• What is T3

  Triiodothyronine, activates thyroid receptors in target tissues, more active form
• What is T4

  Tetraiodothyronine, converted to T3 in liver and muscle
• Hypothyroidism

  Low levels of T4 → impaired growth and development, decreased metabolic activity

  • Lithium can lead to hypothyroidism
• Hyperthyroidism

  High levels of T4 → hyperactivity of organ systems and increased metabolic rate
• Amiodarone can lead to either hypo- or hyper- thyroidism
• Counseling for levothyroxine

  Do NOT switch between brands without letting healthcare provider know and having T4 and TSH levels closely monitored

  • Report s/sx of hyperthyroidism
  • Use caution in pregnancy, infants, elderly, thyroid cancer, pre-existing CV disease, or osteopenia/osteoporosis
• What med is DOC for hypothyroidism

  Levothyroxine (Levoxyl, Synthroid) because its stable, has predictable potency, has long half life so only need once daily dosing

  • Produces physiologic levels of T3 and T4
• What should be monitored while taking levothyroxine

  TSH: check 6-8 weeks after dose change, every 3-6 months during first year and annually thereafter

  T4