Patterns of thyroid enlargement

There are different types of thyroid enlargement (goitres) (1)

• a simple goitre
  • occurs as a result of enlargement of the thyroid gland in response to insufficient amount of thyroid hormone produced to meet the requirement of the body
  • this usually overcomes mild deficiencies of thyroid hormone (1)
  • a simple goitre may be classified as :
  • an endemic (colloid) goitre
  • sporadic (nontoxic) goitre (1)
• endemic (colloid) goitres
  • caused by iodine deficiency (1)
    • iodine is essential to the formation of thyroid hormone
  • seen in people living in geographical areas with iodine-depleted soil ( i.e. away from coastal areas), whose diet is deficient in iodine.
• sporadic (nontoxic) goitres
  • in most cases the cause is unknown (1)
  • occasional causes include:
    • heredity (2)
    • goitrogens - foods such as cabbage, turnips, brussel sprouts, seaweed, and millet (2)
    • drugs like lithium and aminoglutethimide
  • is usually characterized by normal thyroid function (2)
  • many types are seen (2)
    • diffuse (nontoxic)
      • involving the whole thyroid gland
    • multinodular goitres (nontoxic)(4)
      • are common
      • is characterized by soft nodules that grow slowly
      • often asymptomatic
      • may cause difficulty breathing or swallowing
      • nodules indicates a progression of the goitre
        • 95% are benign
        • 5% are malignant (5)
    • a dominant nodule
      • presence of a dominant nodule needs further investigation (4)
      • the greatest concern of a solitary nodule is the possibility of carcinoma
      • it is uncommon, majority are benign adenomas or cysts (6)
• toxic multinodular goitres
  • are caused by the growth of multiple thyroid nodules that produce and secrete excess amounts of thyroid hormone.
  • usually arise from a long-standing simple goitre (3)
• diffuse (toxic) goitres
  • Grave's disease
  • thyroiditis

Reference:

1. Thyroid Goiter(2007). Surgical Unit Of UCLA In Los Angeles. California
2. Nontoxic Nodular Goitre.UPMC, Affiliated with the University of Pittsburgh Schools of the Health Sciences 2007
3. Toxic Nodular Goiter (2007). Surgical Unit Of UCLA In Los Angeles, California
4. Multinodular Goiter Disease (2007)  Johns Hopkins University, School Of Medicine
5. Utiger RD.The Multiplicity of Thyroid Nodules and Carcinomas. New England Journal of Medicine 2005; 352:2376-2378
6. Thyroid Nodules (2007). Johns Hopkins University, School Of Medicine