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Goiter

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goiter thyroid enlargement

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Here is a thorough overview of Goiter drawn from multiple authoritative medical textbooks.

Goiter

Definition

A goiter is any enlargement of the thyroid gland. In common clinical usage the term most often refers to benign causes - diffuse toxic goiter (Graves' disease), toxic multinodular goiter, or nontoxic multinodular goiter. Malignant thyroid enlargement is usually called a mass or nodule rather than a goiter.
  • Goldman-Cecil Medicine, p. 3271
  • Current Surgical Therapy 14e, p. 880

Types

TypeDescription
Diffuse goiterUniform gland enlargement; almost always benign; seen in Graves' disease and congenital hormone synthesis defects
Multinodular goiter (MNG)Multiple nodules, solid or partially cystic (colloid cysts), with areas of fibrosis; may be toxic (hyperthyroid) or nontoxic (euthyroid)
Endemic goiterOccurs in geographic regions of iodine deficiency
Retrosternal / intrathoracic goiterExtension into the chest; can cause superior vena cava syndrome or anterior mediastinal mass

Causes / Pathogenesis

The most common cause worldwide is iodine deficiency. The pituitary responds to low thyroid hormone by increasing TSH secretion, which drives thyroid enlargement. Other causes include:
  • Goitrogens (dietary): bamboo shoots, maize, sweet potatoes
  • Genetic factors and dyshormonogenesis (enzyme defects in thyroid hormone synthesis)
  • Graves' disease (autoimmune, TSH-receptor stimulation)
  • Hashimoto's thyroiditis (autoimmune destruction with compensatory enlargement)
  • Drugs: amiodarone (can cause either hypo- or hyperthyroidism depending on iodine status), lithium
  • Sporadic: in iodine-sufficient areas, the specific cause is often not identified
The thyroid undergoes cycles of activity and regression, leading to nodule formation - some solid, some cystic.
  • Textbook of Family Medicine 9e, p. 315
  • Current Surgical Therapy 14e, p. 880
  • Gray's Anatomy for Students, p. 7340

Clinical Features

  • Painless neck swelling is the classic presentation - the mass moves upward on swallowing (attached to larynx by pretracheal fascia)
  • Compressive symptoms with large goiters:
    • Dyspnea, stridor (inspiratory "crowing" sound from tracheal compression)
    • Dysphagia (esophageal compression)
    • Hoarseness (pressure on larynx or stretching of recurrent laryngeal nerve)
    • Venous congestion / neck discomfort with movement
  • Pemberton's sign: raising both arms above the head causes facial plethora and redness from venous obstruction - a sign of significant substernal extension
  • Tracheal deviation (away from a large unilateral lobe)
  • Hypothyroid symptoms (in large nontoxic MNG): weight gain, bradycardia, lethargy
  • Hyperthyroid symptoms (in toxic MNG or Graves'): palpitations, weight loss, heat intolerance
  • Goldman-Cecil Medicine, p. 3278
  • Current Surgical Therapy 14e, p. 1829
  • Gray's Anatomy for Students, p. 7340-7360

Evaluation

  1. Thyroid function tests: TSH, free T4, T3 - to identify hypo-, hyper-, or euthyroid state
  2. Ultrasound: primary imaging for nodule characterization; features raising malignancy risk:
    • Hypoechogenicity
    • Microcalcifications
    • Hypervascularity
    • Solid component of complex nodule
    • Regional lymphadenopathy
  3. Fine-needle aspiration (FNA): for any sonographically suspicious nodule
  4. CT scan (non-contrast): best for assessing tracheal compression, retrosternal extension, airway geometry - contrast is avoided to prevent iodine load precipitating acute hyperthyroidism
  5. Chest X-ray: tracheal deviation, retrosternal/retrotracheal extension, calcification
  6. Fiber-optic laryngoscopy: for any patient with voice change or prior neck surgery
  7. Flow-volume loop: can detect external tracheal compression
  • Goldman-Cecil Medicine, p. 3278
  • Current Surgical Therapy 14e, p. 1838-1842

CT Imaging Example

CT scans of massive multinodular goiter with retrosternal extension in an 82-year-old man
CT of an 82-year-old man with massive bilateral multinodular goiter (A,B), retrosternal left lobe (C,D), extension below the aortic arch (E, Ao = aorta), and displacement of the right common carotid artery (F). Required manubriotomy for safe resection. - Current Surgical Therapy 14e

Treatment

Indications for Intervention

  • Local compressive symptoms (choking, dyspnea, dysphagia)
  • Partial obstruction of the upper aerodigestive tract
  • Substantial substernal extension (even if asymptomatic) - relative indication, as further growth may require more disruptive surgery later
  • Cosmesis (rarely the sole indication)

Treatment Modalities

ModalityRole
Total or subtotal thyroidectomyDefinitive treatment for large/compressive goiters
Radioactive iodine (RAI)Reduces goiter size ~40-50%; useful in high-risk surgical patients; can transiently worsen compressive symptoms by causing swelling
TSH-suppression with thyroxineLimited role in established MNG; prospective trials show little benefit; side effects (bone loss, arrhythmias) outweigh benefit especially in elderly
Thyroid hormone replacementIndicated when hypothyroidism is present
  • Current Surgical Therapy 14e, p. 1856-1863
  • Goldman-Cecil Medicine, p. 3283

Surgical Complications (Post-Thyroidectomy)

  • Hypocalcemia / tetany: from inadvertent removal or devascularization of parathyroid glands (manifests as tingling in hands, feet, perioral area, and carpopedal spasm)
  • Recurrent laryngeal nerve (RLN) injury: hoarseness, vocal cord paralysis
  • Hemorrhage / hematoma
  • Hypothyroidism: requires lifelong levothyroxine replacement after total thyroidectomy
  • Gray's Anatomy for Students, p. 7368

Key Points at a Glance

  • Goiter = thyroid enlargement; most are benign
  • Leading global cause = iodine deficiency
  • Diffuse goiters are almost always benign; asymmetric/nodular goiters require malignancy workup
  • Pemberton's sign flags substernal compression
  • Non-contrast CT is the gold standard for airway and mediastinal assessment
  • Surgery is the mainstay for compressive or cosmetically significant goiter; TSH suppression has minimal evidence benefit
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