Hashimoto Thyroiditis

Hashimoto thyroiditis is the most common cause of hypothyroidism in iodine-sufficient countries and primary hypothyroidism in adults.

Incidence in USA: Approximately 100,000–400,000 new cases diagnosed each year.

Causes thyroid failure in 10% of pts.

Prevalence increases with age but it is also the most common cause of hypothyroidism in children as young as 1–2 y of age. Individuals between the ages of 30–50 y are most commonly affected.

No documented ethnic predominance.

Gender predominance: F:M ratio 7:4; age 30–50 y.

Increased risk of thyroid storm even if pt is euthyroid preop, as the progressive inflammatory process may cause significant apoptosis of thyroid follicles, leading to the release of thyroid hormone. Life-threatening illness can ensue if hyperthyroidism is severely exacerbated by the stress of operation, typically manifested by hyperpyrexia, tachycardia, and alterations in consciousness.

Risk of respiratory failure or insufficiency and increased bleeding periop.

Chronic hyperthyroidism and its concomitants.

Coexisting autoimmune disease and adrenal failure.

Hashimoto thyroiditis, or chronic autoimmune thyroiditis, involves progressive thyroid dysfunction due to autoimmune-mediated destruction of the thyroid gland through the apoptosis of thyroid epithelial cells. Typical manifestations of the disease may encompass high serum concentrations of antibodies against one or more thyroid antigens, diffuse lymphocytic infiltration of the thyroid, and destruction of the thyroid gland, resulting in thyroid failure.

Chronic inflammation of the thyroid (painful or painless) with lymphocytic infiltration due to autoimmune factors.

Acute inflammation results in increased release of preformed hormone with hyperthyroidism.

Chronic inflammation results in decreased thyroid gland function with resistant hypothyroidism.

Autoantibodies against thyroid peroxidase, thyroglobulin, or TSH receptors causing immune-mediated destruction of thyroid epithelial cells, although a small percentage of pts do not have such antibodies

Associated with other autoimmune diseases, including Sjögren syndrome, SLE, RA, pernicious anemia, autoimmune endocrinopathies, Addison disease, hypoparathyroidism, diabetes mellitus, and gonadal failure

Increased incidence in pts with a family Hx and with chromosomal disorders such as Turner, Down, or Klinefelter syndrome

Also linked to several polymorphisms in genes for HLA and T-cell antigen receptors

Precipitating causes: Thyroid injury (infection, radiation, drugs), stress, steroids, pregnancy, and excessive iodine intake