How does Hashimoto thyroiditis lead to hypothyroidism according to the chapter?

Hashimoto thyroiditis leads to hypothyroidism primarily through an autoimmune process where lymphocytes replace functioning thyroid tissue. As the disease progresses, most patients develop hypothyroidism due to this destruction of thyroid tissue, which impairs hormone production.

Hashimoto thyroiditis, an autoimmune disorder, results in the gradual destruction of thyroid tissue by lymphocytes. Initially, patients may be euthyroid, but over time, as more thyroid tissue is replaced by lymphocytes, they typically progress to hypothyroidism. This condition is characterized by high levels of thyroid autoantibodies and often presents as a goiter. By the time the diagnosis is made, most individuals are already hypothyroid and require hormone replacement therapy.