Which diseases may show positive results with agglutination assays for antibodies to thyroid peroxidase?

Agglutination assays for antibodies to thyroid peroxidase are primarily used to detect autoimmune thyroid diseases, where the body produces antibodies against its own thyroid tissue. The presence of these antibodies is notably associated with Graves' disease and Hashimoto's thyroiditis.

In Graves' disease, hyperthyroidism often occurs due to the stimulating effect of thyroid-stimulating immunoglobulins, but antibodies to thyroid peroxidase can also be present as part of the autoimmune response. In Hashimoto's thyroiditis, which typically leads to hypothyroidism, the presence of thyroid peroxidase antibodies is a hallmark finding as they contribute to the destruction of thyroid gland tissue.

Other diseases listed, such as myasthenia gravis, granulomatous thyroid disease, and Addison's disease, do not typically involve the production of antibodies against thyroid peroxidase. Myasthenia gravis primarily affects the neuromuscular junction and is associated with antibodies to acetylcholine receptors. Granulomatous thyroid disease, such as de Quervain's thyroiditis, involves a different pathophysiological mechanism that does not involve these antibodies. Addison's disease, a disorder of the adrenal glands, does not correlate with thyroid peroxidase antibodies either.

Thus