Goiter

Goiter is any abnormal enlargement of the thyroid gland. The condition has various causes, with the most common worldwide being iodine deficiency. In the US, however, Hashimoto's and Graves' disease are more common etiologies. Goiters can be classified based on their morphology, function, or dignity (benign or malignant). Symptoms depend on etiology and are often absent. However, patients may present with hyperthyroidism or hypothyroidism. Large goiters may also cause obstructive symptoms due to compression of the trachea and/or the esophagus. Diagnosis is established based on clinical examination, laboratory tests, and imaging techniques. Management depends on the underlying condition and may include administering iodine (for treating nontoxic euthyroid goiter) or performing surgery (e.g., for treating local compression or thyroid cancers).

• Sex: ♀ > ♂ (4:1)
• Frequency: decreases with age

Epidemiological data refers to the US, unless otherwise specified.

• Iodine deficiency (leading cause of goiter worldwide)
• Inflammation (e.g., Hashimoto thyroiditis, subacute granulomatous thyroiditis)
• Graves disease
• Thyroid cysts (e.g., thyroglossal cyst)
• Thyroid adenomas
• Thyroid carcinomas
• Ingestion of goitrogens (e.g., lithium carbonate)
• Elevated TSH production (e.g., pituitary adenoma, paraneoplastic syndrome)
• Congenital goiter

Thyroid gland versus goiter

• Normal adult thyroid gland
  • Weight: ∼ 20–30 g
  • Volume: ∼ 7–10 mL
  • Location: caudal to larynx surrounding the anterolateral part of the trachea
• Goiter
  • Enlarged volume of thyroid gland
  • Goiters can be differentiated based on
    • Morphology (growth pattern, size)
    • Thyroid function
    • Benignity/malignancy

Morphology

• Growth pattern of goiter
  • Diffuse goiter: diffusely enlarged thyroid
    • Graves disease
    • Inflammation (e.g., Hashimoto thyroiditis)
    • TSH-secreting pituitary adenoma
    • Iodine deficiency
  • Nodular goiter: irregular enlarged thyroid due to nodule formation
    • Uninodular goiter (e.g., cysts, adenoma, cancer)
    • Toxic and nontoxic multinodular goiter
• Goiter size: see ”Classification of goiter by palpation” below.

Thyroid function of goiter

• Nontoxic goiter: normal TSH, fT₃, and fT₄ levels
  • E.g., Iodine deficiency
• Toxic goiter: increased thyroid hormone production
  • E.g., Graves disease, toxic multinodular goiter
• Hypothyroid goiter: decreased thyroid hormone production
  • E.g., Hashimoto's disease, congenital hypothyroid goiter

Dignity of goiter

• Malignant goiter: e.g., thyroid carcinoma
• Benign (bland) goiter: benign thyroid enlargement

References:^[1][2]

• Patients are commonly asymptomatic.
• Altered hormone metabolism may occur
  • Symptoms of hyperthyroidism
  • Symptoms of hypothyroidism
• Obstructive symptoms
  • Compression of the trachea → exertional dyspnea and, in severe cases, stridor or wheezing
  • Compression of the esophagus → dysphagia
• Potentially:
  • Lymph node enlargement (e.g., cervical lymph nodes) in malignant infiltration
  • Pemberton sign: a physical examination finding in patients with goiter (bilateral arm elevation results in facial plethora due to an obstructed thoracic inlet that increases venous pressure)

• Best initial step: palpation of thyroid gland (see “Classification of goiter by palpation” below)
• Laboratory tests
  • Initial workup: TSH levels
  • Possible screen for thyroid antibodies (see thyroid antibodies)
  • If medullary carcinoma is suspected, check calcitonin levels (see thyroid cancer).
• Imaging: determination of goiter size, nodularity, and consistency
  • Ultrasound
  • Further evaluation may include: CT, MRI
• Interventions
  • Depend on the suspected pathology
  • Fine-needle biopsy for cytology

Classification of goiter by palpation

According to the World Health Organization (WHO) classification:

• Grade 0: no goiter is palpable or visible.
• Grade 1: palpable goiter, not visible when neck is held in normal position
• Grade 2: a clearly swollen neck (also visible in normal position of the neck) that is consistent with a goiter on palpation

References:^[3]

• Nontoxic goiter
  • Treatment is not needed if the patient is asymptomatic.
  • Schedule follow-ups for possible dysfunctional thyroid and/or obstructive symptoms.
• Large goiter (> 80 mL)
  • Surgery is preferred to avoid complications (e.g., obstructive symptoms).
  • Alternatively, radioiodine therapy
• Iodine deficiency: iodine supplementation
• In other cases, goiter treatment varies depending on the exact etiology (see “Etiology” above).