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 goiter may be classified as :
  • an endemic (colloid) goiter
  • sporadic (nontoxic) goiter (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 cuases 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 goiter
        • 95% are benign
        • 5% are malignant (5)
    • a dominant nodule
      • presence of a dominant nodule needs futher 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 goite (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