What are the causes of child goiter?

Causes of Child Goiter

The primary cause of child goiter worldwide is iodine deficiency, though in developed countries with adequate iodine intake, autoimmune thyroiditis (Hashimoto's disease), genetic factors, and other nutritional deficiencies are more common causes. 1, 2

Main Causes of Goiter in Children

Nutritional Factors

• Iodine deficiency: The most common cause globally, responsible for endemic goiter in developing countries 2, 3
• Iodine excess: Paradoxically, excessive iodine intake can also cause goiter 4, 5
• Other micronutrient deficiencies:
  • Selenium deficiency impairs thyroid hormone metabolism 6
  • Iron deficiency impairs thyroid metabolism 6, 1

Autoimmune Causes

• Hashimoto's thyroiditis (chronic autoimmune thyroiditis): Most frequent cause in industrialized nations with adequate iodine intake 6
• Graves' disease: Can cause diffuse goiter with hyperthyroidism 6

Genetic Factors

• DICER1 gene mutations: Associated with multinodular goiter development, with cumulative incidence of 13% in males and 32% in females by age 20 1
• Familial forms: Strong genetic predisposition in certain families 1
• Congenital hypothyroidism: Can lead to goiter if untreated 6

Other Causes

• Exposure to goitrogens: Substances that interfere with thyroid hormone production
  • Found in certain foods (cruciferous vegetables, soy) 1
• Environmental factors: Smoking increases risk 1, 7
• Thyroid nodules: Can develop in children, requiring evaluation for malignancy 7
• Medications: Some drugs can induce goiter, including potassium iodide in rare cases 5

Clinical Presentation

Children with goiter may present with:

• Visible or palpable neck mass
• Difficulty swallowing (dysphagia)
• Difficulty breathing (dyspnea)
• Voice changes or hoarseness
• Symptoms of hypothyroidism (fatigue, cold intolerance, constipation)
• Symptoms of hyperthyroidism (if toxic goiter)
• In severe iodine deficiency: developmental delays, intellectual disability (cretinism) 6, 1

Evaluation of Child Goiter

1. Laboratory assessment:

   • TSH is the recommended initial test 6
   • Free T4 or Free T4 Index should be measured in suspected hypo/hyperthyroidism 6
   • Urinary iodine excretion (24-hour collection) to assess iodine status 6
   • Thyroid antibodies if autoimmune disease suspected

2. Imaging:

   • Thyroid ultrasound is the first-line imaging study to evaluate morphology 6, 1
   • Scintigraphy (radioiodine uptake) if hyperthyroidism is present 1
   • CT or MRI if substernal extension or tracheal compression is suspected 1

Management Considerations

Treatment depends on the underlying cause:

• Iodine deficiency: Iodine supplementation, particularly in the first and second trimesters to prevent neurological abnormalities 6
• Autoimmune thyroiditis:
  • Hypothyroidism: Levothyroxine replacement therapy 6, 1
  • Hyperthyroidism: Thionamides (propylthiouracil or methimazole), radioactive iodine (in older children), or surgery 6
• Nodular goiter: Evaluation with ultrasound and possible fine-needle aspiration for suspicious nodules 1, 7
• Compressive symptoms: Surgical intervention may be necessary 1

Important Caveats

• Iodine supplementation should be used cautiously as excess iodine can paradoxically cause or worsen goiter 5, 4
• Children under 1 month of age are more likely to develop hypothyroidism from iodide exposure 5
• Patients with pre-existing thyroid disease are more susceptible to adverse effects from iodine supplementation 5
• Untreated congenital hypothyroidism can lead to cretinism, but early detection through newborn screening and prompt treatment can result in nearly normal intelligence and growth 6

Understanding the specific cause of goiter is essential for appropriate management and to prevent complications related to thyroid dysfunction in children.