Goiter, Simple or Nontoxic (Diffuse & Multinodular)

• • May be a diffuse or a multinodular goiter

  • May be physiologic or pathophysiologic

  • -Physiologic occurs during puberty, menses, or pregnancy

    -Pathophysiologic is due to iodine-deficiency, congenital defect in thyroid hormone production, or goitrogenic foods or drugs

  • Generally assumed to be compensatory response to inadequate thyroid hormone production

  • Thyroid growth immunoglobulins may also be important

  • Food goitrogens include isothiocyanate and goitrin (in milk products)

  • Drugs implicated as goitrogens include:

  • -Lithium

    -p-Aminosalicylic acid

    -Aminoglutethimide

    -Sulfonamides

    -Phenylbutazone

  • Congenital determined failures in thyroid hormone metabolism include iodine transport defects, abnormal secretion of iodoproteins, and thyroid hormone resistance syndromes

Epidemiology

• • Prevalence of about 5%; increases with age and in women

Symptoms and Signs

• • Neck mass

  • Inspiratory stridor

  • Dyspnea

  • Dysphagia

  • Symmetrically enlarged thyroid with smooth surface, or enlarged thyroid with multiple nodules

  • Enlargement and prominence of the large veins of the neck and upper thorax

Laboratory Findings

• • Thyroid function tests usually normal

  • Thyroid-stimulating hormone (TSH) may be suppressed slightly, and radioiodine uptake increased

Imaging Findings

• • US reveals size and extent of goiter; can define focal nodules

  • CT or MRI can define retrosternal or intrathoracic extension but are not considered as primary diagnostic tools

  • Thyroid scintigraphy can confirm extension and functional status of the gland

  • Chest radiograph may demonstrate an anterior mediastinal mass, with or without tracheal deviation, in the setting of a substernal goiter

• • As the goiter persists, nodules can develop

Rule Out

• • Thyroid malignancy or lymphoma

  • Acute suppurative thyroiditis

  • Silent thyroiditis

  • Subacute thyroiditis

  • Reidel thyroiditis

• • Complete history and physical exam

  • Thyroid function tests

  • Thyroid US for cervical goiter

  • CT scan of neck and chest for substernal extension

  • Fine-needle aspiration biopsy of any concerning nodule

• • Goiter usually responds favorably to thyroid hormone administration

  • Multinodular goiter can be treated with operative removal, thyroid hormone administration, or radioactive iodine therapy

  • Operative candidates with tracheal compression or deviation should undergo awake, fiberoptic intubation

Surgery

Indications

• • Relief of local compressive symptoms

  • Diagnostic to rule out cancer in areas of hardness or rapid growth

  • Proven malignancy

Medications

• • Suppressive thyroxine (T4)

  • Radioactive iodine 131

Treatment Monitoring

• • Long-term suppressive/replacement thyroid hormone therapy

  • Monitor TSH and T4

Prevention

• • Long-term administration in diet (to prevent iodine-deficiency goiter)

  • Limit intake of natural or pharmacologic goitrogens

References