Iodine-induced thyroiditis and hypothyroidism in the hemithyroidectomized BB/W rat

Area of Science:

• Endocrinology
• Immunology
• Genetics

Background:

• Iodine excess can trigger hypothyroidism in humans with Hashimoto's thyroiditis.
• Previous studies showed iodine administration increased lymphocytic thyroiditis (LT) in BB/W rats without hypothyroidism.
• Hemithyroidectomy was performed to assess iodine's effect on reduced thyroid mass.

Purpose of the Study:

• To investigate if reducing thyroid mass in BB/W rats leads to iodine-induced hypothyroidism.
• To explore the role of genetics in iodine-induced thyroid dysfunction.
• To establish a rat model for studying iodine-induced hypothyroidism.

Main Methods:

• Administered 0.05% iodine in drinking water to hemithyroidectomized BB/W rats and control strains (W-line, Wistar-Furth, Sprague-Dawley).
• Monitored antithyroglobulin antibodies, LT incidence, thyroid weight, and thyroid hormone levels (T4, T3, TSH).
• Compared results between BB/W rats and control strains.

Main Results:

• Hemithyroidectomized BB/W rats showed increased LT incidence, antithyroglobulin antibodies, and hypothyroidism.
• Iodine did not induce LT or antibodies in W-line, Wistar-Furth, or Sprague-Dawley rats.
• W-line rats developed thyroid enlargement and hypothyroidism without LT, suggesting a genetic factor.

Conclusions:

• Hemithyroidectomy in BB/W rats creates a model for iodine-induced LT and hypothyroidism, similar to human Hashimoto's thyroiditis.
• Iodine-induced hypothyroidism in rats may be genetically determined, as observed in W-line rats.
• Further research is needed to elucidate the genetic mechanisms underlying iodine-induced hypothyroidism.