Home | Orthoiodosupplementation | Body | Disease | Special | Overviews

Thyroid Physiology  

Thyroid Disease

Goiter

• Abraham

• Brix

• Dugrillon, Gartner, Pisarev

• Flechas

• Furlanetto

• Hennemen

• Hintze

• Jooste

• Kahaly

• Koutras, Papanastasiou

• Kreissl

• Lee

• McClendon

• Meng

• Rasmussen

• Shomon

• Stubner

• Studer, Derwahl

• Wolff

Lee

Goiter, Nontoxic

Lee SL

eMedicine

"A nontoxic goiter is a diffuse or nodular enlargement of the thyroid gland that does not result from an inflammatory or neoplastic process and is not associated with abnormal thyroid function. Endemic goiter is defined as thyroid enlargement that occurs in more than 10% of a population, and sporadic goiter is a result of environmental or genetic factors that do not affect the general population....

"The histopathology varies with etiology and age of the goiter. Initially, uniform follicular epithelial hyperplasia (diffuse goiter) is present with an increase in thyroid mass. As the disorder persists, the thyroid architecture loses uniformity, with the development of areas of involution and fibrosis interspersed with areas of focal hyperplasia. This process results in multiple nodules (multinodular goiter). On nuclear scintigraphy, some nodules are hot, with high isotope uptake (autonomous) or cold, with low isotope uptake, compared with the normal thyroid tissue. The development of nodules correlates with the development of functional autonomy and reduction in thyroid-stimulating hormone (TSH) levels. Clinically, the natural history of a nontoxic goiter is growth, nodule production, and functional autonomy resulting in thyrotoxicosis in a minority of patients....

"

Endemic goiters associated with iodine deficiency are associated with sometimes immense thyroid hypertrophy, hypothyroidism, and cretinism (see Iodine Deficiency). Sporadic goiters are generally asymptomatic and found either by a clinician's physical examination or by the patient's observation of neck enlargement. Occasionally, the goiter may cause symptoms due to pressure on anterior neck structures, including the trachea (wheezing, cough, globus hystericus [anterior neck pressure]), the esophagus (dysphagia), and the recurrent laryngeal nerve (hoarseness).  Rarely, the obstruction can be dangerous because of narrowing of the trachea and the development of tracheitis with edema and tracheomalacia, leading to severe narrowing of the airway with serious obstruction resulting in a respiratory emergency.

"The most common worldwide cause of endemic nontoxic goiter is iodine deficiency. However, in patients with sporadic goiter, the cause is usually unknown. Nontoxic goiters have many etiologies, including the following:

• Iodine deficiency: Goiter formation occurs with moderately deficient iodine intake of less than 50 mcg/d. Severe iodine deficiency associated with intake of less than 25 mcg/d is associated with hypothyroidism and cretinism.

• Iodine excess: Goiter formation due to iodine excess is rare and usually occurs in the setting of preexisting autoimmune thyroid disease.

• Goitrogens

• • Drugs - Propylthiouracil, lithium, phenylbutazone, aminoglutethimide, iodine-containing expectorants

     

  • Environmental agents - Phenolic and phthalate ester derivatives and resorcinol found downstream of coal and shale mines

     

  • Foods - Vegetables of the genus Brassica (eg, cabbage, turnips, brussels sprouts, rutabagas), seaweed, millet, cassava, and goitrin in grass and weeds

• Dyshormonogenesis: A defect in the thyroid hormone biosynthetic pathway is inherited.

• Childhood head and neck radiation: Radiation exposure during childhood results in benign and malignant nodules.

 Home | Orthoiodosupplementation | Body | Disease | Special Topics | Overviews  

The Iodine Group | Books | Disclaimers | Contact Us | Search  

  Copyright: Zoe, 2006.