Goiter

A goiter is an abnormal enlargement of the thyroid gland. It may appear as a diffuse, uniform swelling or as a nodular enlargement with one or more nodules.

Diffuse goiters often result from chronic stimulation of thyroid tissue, which may develop due to elevated TSH levels, immune-mediated activation, or iodine deficiency.

In hyperthyroid goiters, such as those seen in Graves’ disease, autoantibodies called thyroid-stimulating immunoglobulins bind to TSH receptors, triggering excess hormone production.

In hypothyroid goiters, chronic elevation of TSH may develop due to autoimmune destruction of the thyroid, as seen in Hashimoto’s thyroiditis, or certain medications such as lithium.

Genetic defects affecting thyroid hormone synthesis can also lead to congenital goiters.

Over prolonged periods of stimulation, diffuse goiters may gradually become nodular and may eventually develop autonomous hormone production, resulting in toxic multinodular goiter. As goiters enlarge, they may exert mass effect on adjacent structures, leading to difficulty breathing or trouble swallowing.