Hyperthyroidism Management Quiz

Hyperthyroidism

• Thioamides (e.g., Propylthiouracil, Methimazole):

  • Mechanism of Action (MOA): Inhibit thyroid hormone production by preventing iodine from binding to tyrosine residues, inhibiting coupling of MIT and DIT.
  • Side Effects: Common: gastrointestinal upset, rash, joint pain; Serious: agranulocytosis (0.4% of patients, with a higher risk in the first 90 days), neutropenia.
  • Propylthiouracil: Not commonly used for long-term treatment; has a role in the treatment of pregnant patients, but is less effective and carries risks.
  • Methimazole: More commonly used for long-term treatment.
  • Dosing: Varies by severity (mild, moderate, severe), with initial and maintenance doses adjusted accordingly.

• Beta-Blockers:

  • MOA: Reduce symptoms related to cardiac overstimulation, do not directly influence thyroid hormones.
  • Use: Many beta-blockers are suitable except for those with intrinsic sympathomimetic activity.
  • Side Effects: Not typically directly related to thyroid function; some may worsen underlying cardiovascular conditions.
  • Note: Beta-blockers do not directly treat the underlying hyperthyroidism; they just treat symptoms.

• Surgery:

  • Use: Used as a curative treatment due to permanent hypothyroidism in some cases. May be accompanied by temporary thyroiditis or a return to worsened hyperthyroidism symptoms, then eventual hypothyroidism.

• Radioactive Iodine:

  • Use: Curative treatment for hyperthyroidism, leading to temporary thyroiditis then eventual restoration of thyroid function or hypothyroidism.

Hypothyroidism

• Desiccated Thyroid:

  • Use: First agent, derived from animal thyroids. Contains T3 and T4; considered a potentially less stable preparation with less predictable pharmacokinetics.

• Liothyronine:

  • Use: Analog of T4; quicker action, primarily for use in cases with conversion issues from T4 to T3.

• Levothyroxine:

  • Average Dose: 1.6 mcg/kg/day, with varying initial dosages (12.5 mcg upward); titrated based on TSH levels. Higher TSH correlates to higher T4 dosage.
  • Starting Dosage Recommendation: Cautious increases based on age, pre-existing cardiac conditions, severity of hypothyroidism, and other factors. Start low, up to 12.5 -50mcg, and advance as tolerated and monitored.
  • Considerations: Administer on an empty stomach; avoid concurrent use with certain medications/nutrients.
  • Side Effects: Relatively few if the medication is dosed correctly, and monitoring is conducted; common side effects include hyperthyroidism symptoms and cardiac issues if dosages are too high.