What are the symptoms and treatment options for hyperthyroidism?

Symptoms and Treatment of Hyperthyroidism

Hyperthyroidism is characterized by tremors, nervousness, insomnia, excessive sweating, heat intolerance, tachycardia, hypertension, and goiter, with treatment options including beta-blockers, antithyroid medications, radioactive iodine therapy, or surgery depending on the cause and severity. 1

Common Symptoms

• Cardiovascular symptoms: Tachycardia, palpitations, hypertension, increased cardiac output, and potential atrial fibrillation 1, 2
• Neuropsychiatric symptoms: Nervousness, anxiety, insomnia, hyperactivity, and tremors 1, 3
• Metabolic symptoms: Unintentional weight loss, heat intolerance, and excessive sweating 1, 4
• Gastrointestinal symptoms: Diarrhea and increased appetite 4
• Physical findings: Goiter (enlarged thyroid gland), exophthalmos (bulging eyes in Graves' disease), and hair loss 1, 4

Cardiovascular Complications

• Decreased systemic vascular resistance and increased cardiac output are hallmark hemodynamic changes 2
• Severe, long-standing hyperthyroidism can lead to heart failure, especially in conjunction with persistent tachycardia or rapid atrial fibrillation 5, 2
• Cardiovascular complications are the chief cause of death after treatment of hyperthyroidism in patients over 50 years of age 2

Treatment Options

First-Line Treatment

• Beta-blockers (such as atenolol or propranolol) should be initiated first to control heart rate, reduce tremors, and mitigate cardiovascular symptoms 1, 2
  • The goal is to lower heart rate to nearly normal, improving the tachycardia-mediated component of ventricular dysfunction 2
  • Beta-blockers provide rapid symptomatic relief while definitive treatment takes effect 2

Definitive Treatment Options

1. Antithyroid medications:

   • Methimazole is the preferred first-line antithyroid drug for most patients 4, 6
   • Propylthiouracil is indicated for patients intolerant to methimazole or during the first trimester of pregnancy 7
   • Long-term treatment (5-10 years) with antithyroid drugs is associated with fewer recurrences (15%) than short-term treatment (12-18 months) 8

2. Radioactive iodine therapy:

   • Most widely used definitive treatment in the United States 6
   • Particularly effective for toxic nodular goiter 8
   • Results in permanent hypothyroidism requiring lifelong thyroid hormone replacement 9

3. Surgical thyroidectomy:

   • Option for patients with large goiters, suspected malignancy, or when other treatments are contraindicated 6
   • Also results in permanent hypothyroidism requiring lifelong thyroid hormone replacement 9

Special Considerations

Pregnancy

• Hyperthyroidism during pregnancy increases risk of severe preeclampsia, preterm delivery, and heart failure 1
• Propylthiouracil may be preferred during the first trimester, but switching to methimazole for the second and third trimesters should be considered due to potential hepatotoxicity with propylthiouracil 7

Severe Complications

• Thyroid storm: A rare but life-threatening emergency characterized by extreme hyperthyroidism with systemic decompensation and hyperpyrexia 1, 9
• Liver damage: Propylthiouracil can cause severe liver problems including liver failure requiring transplantation, especially in pediatric patients 7
• Agranulocytosis: Patients on antithyroid medications should be monitored for symptoms such as sore throat, fever, or general malaise 7

Monitoring During Treatment

• Thyroid function tests should be monitored periodically during therapy 7
• An elevated serum TSH indicates that a lower maintenance dose of antithyroid medication should be employed 7
• Patients on propylthiouracil should be monitored for signs of hepatic dysfunction, especially in the first six months of therapy 7

Drug Interactions

• Antithyroid medications may interact with:
  • Anticoagulants (increased effect of warfarin) 7
  • Beta-blockers (altered clearance when becoming euthyroid) 7
  • Digitalis glycosides (increased serum levels when becoming euthyroid) 7
  • Theophylline (decreased clearance when becoming euthyroid) 7