What is the treatment for toxic goiter (hyperthyroidism) in children?

Treatment of Toxic Goiter in Children

The first-line treatment for toxic goiter (hyperthyroidism) in children is antithyroid drug (ATD) therapy, typically with methimazole, for an initial course of 12-24 months.

Diagnosis and Initial Assessment

• Toxic goiter in children is most commonly caused by Graves' disease (~96% of pediatric cases) 1
• Diagnostic workup should include:
  • Thyroid function tests (TSH, free T4)
  • Anti-TSH receptor antibodies (to confirm Graves' disease)
  • Thyroid ultrasound to assess goiter size and characteristics
  • Radionuclide uptake scan may be helpful in differentiating causes of thyrotoxicosis 2

Treatment Algorithm

First-Line Treatment: Antithyroid Drugs (ATDs)

• Methimazole (MMI) is the preferred ATD in children due to lower risk of serious adverse effects compared to propylthiouracil (PTU) 3, 1

• Initial dosing:

  • Starting dose: 0.5-1 mg/kg/day divided into 1-2 doses
  • Maximum daily dose: 30 mg
  • Once stabilized, can often be reduced to once-daily dosing 4

• Monitoring during ATD therapy:

  • Check TSH and free T4 every 4-6 weeks until stable, then every 3-6 months
  • Monitor for adverse effects, particularly within first 3 months (when 91.6% of adverse events occur) 5
  • Common side effects: rash, urticaria, arthralgia, GI symptoms
  • Rare but serious side effects: agranulocytosis, hepatotoxicity

• Duration of therapy:

  • Continue for 12-24 months before attempting discontinuation
  • Remission rates with ATDs in children: 25-46% 5, 6
  • Longer treatment duration (up to 5 years) may increase remission rates 5

Second-Line Treatments (for treatment failures or complications)

When to consider definitive therapy:

1. Failure to achieve remission after 12-24 months of ATD therapy
2. Major adverse reactions to ATDs
3. Poor medication adherence
4. Severe disease or very large goiter

Radioactive Iodine (RAI) Therapy

• Generally used for children >10 years old who fail medical therapy 1
• Results in permanent hypothyroidism in approximately 66% of patients 3
• Requires lifelong levothyroxine replacement therapy
• May worsen thyroid eye disease in 15-20% of patients

Surgical Treatment (Total or Near-Total Thyroidectomy)

• Consider for:
  • Children <5 years old with severe disease 1
  • Very large goiters
  • Severe ophthalmopathy
  • Failure of medical and RAI therapy
• Results in permanent hypothyroidism requiring lifelong levothyroxine
• Surgical risks include hypoparathyroidism and recurrent laryngeal nerve damage

Special Considerations

• Continuous low-dose ATD therapy: For patients who relapse but refuse definitive therapy, long-term low-dose MMI (mean 4.6 mg daily) can be considered as an alternative management strategy 3

• Monitoring for associated conditions:

  • Screen for other autoimmune conditions that commonly co-occur with autoimmune thyroid disease 7
  • Monitor for thyroid eye disease and treat appropriately

• Caution in specific populations:

  • Neonatal Graves' disease (from maternal antibodies) typically resolves within 3-6 months
  • Adolescent females should be counseled about contraception during ATD therapy due to potential teratogenic effects

Prognosis

• Untreated thyrotoxicosis in children can cause irreversible damage to the central nervous system and multiple organ systems 1
• Early and appropriate treatment is essential for optimal outcomes
• Many children will eventually require definitive therapy (RAI or surgery) as remission rates with ATDs are relatively low (25-46%) 5, 6

Common Pitfalls

1. Delaying treatment while awaiting complete diagnostic workup
2. Failing to monitor for adverse effects of ATDs, particularly in the first 3 months
3. Discontinuing ATDs too early (before 12-24 months)
4. Not recognizing that most children will eventually require definitive therapy
5. Inadequate follow-up monitoring of thyroid function tests