in man, enlargement of the thyroid gland caused by the proliferation of its functional lymphoid tissue (parenchyma) or of its connective-tissue stroma. The proliferation of thyroid epithelium may embrace the entire thyroid parenchyma (diffuse goiter), or it may originate in a particular portion of the parenchyma (nodular goiter). Slight enlargement of the gland may occur in puberty or during menstruation, pregnancy, and lactation. Goiter may be associated with a number of conditions—diffuse toxic goiter, thyroiditis, thyroid tumor, and sporadic and endemic goiter.
A goiter may be unilateral or bilateral. Most often it is found in the neck; sometimes it is located behind the sternum (substernal goiter). A goiter usually alters the contours of the neck; although with substernal and deep-lying goiters the contours of the neck may remain normal. A goiter results in malfunction of the thyroid gland, but in the euthyroid form there need not be any functional impairment. Sporadic goiter is found in a number of localities and is caused by an endogenous (depending on internal factors) iodine deficiency in the body. Endemic goiter is found in certain biogeochemical areas where there is an insufficiency of iodine in the air, water, soil, and food products (instead of 200–220 μg, 20–80 μg of iodine or less enters the human body). Insufficiency of iodine in the environment may be aggravated by unfavorable exogenous (social, everyday, and sanitary-hygienic conditions) or endogenous (pregnancy, lactation, hypovitaminoses, helminthiases) factors. Iodine deficiency may result from infectious diseases or intoxications. A relative deficiency may occur when the ratio of iodine to certain chemical compounds (calcium, fluorine, and so forth) in the body is upset. Endemic goiter is found in almost every country, especially in mountainous regions, valleys, foothills, and watersheds and in swampy, sandy, and peaty regions. It is almost never found in chernozem zones.
Goiter prevention includes correcting unhealthy conditions in the throat and mouth, vermifuge treatment, and improvement of the conditions of sanitation and hygiene of daily life (keeping dwellings clean, maintaining the water supply properly, sound nutrition); individual and group iodine prophylaxis (iodized table salt); and early detection and dispensary observation of goiter patients. Treatment, depending on the form and symptoms of goiter, includes iodine preparations, thyroidin, triiodothyronine, and diiodothyrosine. Surgery is indicated for nodular and mixed goiter; it is also recommended for diffuse goiter if more conservative treatment proves ineffective.
L. M. GOL’BER