Role of Iodine, Sodium Chloride and Antithyroid Drugs in the Development of Goiter in the Rat

Abstract

In an attempt to study the possible role of goitrogens, NaCl and iodine in the development of goiter, graded doses of methylthiouracil (MTU) and 2% of NaCl were given to rats fed low and relatively high iodine diets for 14 days. Small amounts of MTU produced goiter with normal or slightly high radioiodine uptake and suppressed triiodothyronine +thyroxine (T3 + T4) formation in animals fed a low iodine diet. NaCl was also goitrogenic and suppressed T3 + T4 synthesis in animals fed a low iodine diet. Although significant goiter occurred with MTU and NaCl treatment, serum PBI was fairly normal in all groups. However, these goitrogenic and suppressive effects on thyroidal T3 + T4 formation by small amounts of MTU or NaCl did not appear in animals fed a relatively high iodine diet. Even when large amounts of MTU were given, the increase in thyroid size and the depression of T3 +T4 formation were significantly greater in animals fed a low iodine diet than in those on a relatively high iodine diet. It is suggested that simple goiter may be produced in man by a diet containing the minimal requirement of iodine and small amounts of naturally occurring goitrogen.