Treatments of Hyperthyroidism: Radioactive Iodine Therapy and Surgery
• Ameliorate several of the clinical manifestations of hyperthyroidism.
• Also impair conversion of T4 to T3.
• Propranolol (80 mg/d), atenolol (50 mg/d), metoprolol (50 mg/d), or nadolol (40mg/d) are possible drug choices with their usual starting doses.
• The dose of B-blocker can be titrated to relieve the symptoms of hyperthyroidism (anxiety, palpitations, tremor, nervousness, and heat intolerance).
• Calcium channel blockers, such as diltiazem, can be substituted if B-blockers are contraindicated.
Radioactive Iodine Therapy
• Most widely used treatment for adults with thyrotoxicosis in the United States.
• I-131 is the isotope of choice. It is administered orally as a capsule or a liquid. I-131 is effective as a single dose approximately 90% of the time. The typical dose range is 5 to 15 mcg. It takes 3 to 6 months for the patient to achieve a euthyroid or hypothyroid state after administering I-131.
• Relative Contraindications
• It is advisable to avoid pregnancy for 6 to 12 months after I-131 therapy
- There are no known adverse effects on the health of offspring of treated patients.
• Hypothyroidism will probably occur after therapy (50% in 10 years)
Surgery for Hyperthyroidism
• Subtotal or total thyroidectomy is the oldest form of therapy for thyrotoxicosis.
• Very infrequently used today.
• Surgery is limited to special circumstances
- Middle trimester of pregnancy
- Patients with large goiters
- Patients with Graves ophthalmopathy
- Patient choice
• Mortality is close to zero
- Recurrent laryngeal nerve damage
- Hypoparathyroidism (transient or permanent) and hypocalcemia
• Preoperative preparation
- Use ATDs to induce a euthyroid state
- Potassium iodide (SSKI) or Lugol’s solution for 10 days prior to surgery
- B-Adrenergic antagonists are also administered
Hyperthyroidism and Pregnancy and Lactation
• ATD therapy with PTU is the treatment of choice
• MMI is an acceptable alternative, but it has been associated with minor birth defects (aplasia cutis).
• ATDs are not believed to be teratogenic, however, neonatal thyroid function may be affected by transplacental passage of the ATD.
• The free T4 and free T3 are controlled to slightly above the normal range to minimize the dose of ATD.
• Thyroid function tests are monitored every 4 weeks.
• Graves disease often spontaneously improves in the later months of pregnancy.
• B-Adrenergic antagonists can be used to alleviate symptoms.
• Rare complication of poorly controlled hyperthyroidism.
• Potentially fatal.
• Pathogenesis is unknown.
• It is a clinical diagnosis—lab tests are done to confirm the clinical impression.
Large doses of ATDs: PTU 300 to 400 mg every 4 hours by mouth (PO)
Iodine: SSKI 3 to 5 drops every 6 hours orally
Dexamethasone 8 mg IV daily until adrenal insufficiency is ruled out
B-adrenergic antagonists either IV or PO