Histopathology of the thyroid in amiodarone‐induced hypothyroidism

Abstract

Amiodarone is well recognized as an anti-arrhythmic drug containing a high dose of iodine with considerable potential to cause thyroid dysfunction. The present patient was a 66-year-old Japanese woman who developed a cardiac arrhythmia and was given amiodarone as an anti-arrhythmic agent for approximately 3 months, until the day before her death. However, 19 days after starting amiodarone, serum testing indicated a hypothyroid status that was not recognized clinically. At autopsy, microscopy showed that most of the thyroid follicles were enlarged with dense colloid substance and lined by flattened follicular cells (involuted follicles). There were a small number of damaged follicles infiltrated by macrophages, which were immunopositive for HAM56. Sudan IV staining indicated many lipid droplets in follicular cells. Ultrastructurally the follicular cells contained large residual bodies composed of abundant electron-lucent lipid droplets of variable size. Although it is difficult to be certain of the direct link of amiodarone on the basis of a single case, it is reasonable to presume that this histopathology is associated with amiodarone-induced hypothyroidism and that involution changes represent the hypofunctional status of this drug-induced disorder. This is the first report on the histopathological findings of thyroid tissue from a patient with amiodarone-induced hypothyroidism.

Iodine increases and predicts incidence of thyroiditis in NOD mice: Histopathological and ultrastructural study

“…Distended rough endoplasmatic reticulum and mitochondrial lesions with a loss of cristae were described by Nakazawa et al (13) in humans following the use of amiodarone for 19 days. Since no subcellular lesions were observed in the control groups (CG60 and CG90), it is possible that the ultra-structural degeneration is an iodine-induced event.…”

“…Several sources of iodine induced thyroiditis were correlated with the development of thyroid autoantibodies (8), including iodinated radiological contrasts (9–12) and medical drugs (13). However, the role of iodine in these processes remains controversial and not fully understood.…”

Vitamin E Ameliorates the Toxic Effect of Amiodarone on Thyroid Gland in Rats: A Histological and Ultrastructural Study

“…Many follicular cells contained vacuoles and yellowish pigment in the cytoplasm. Few inflammatory cells and small collections of fibrosis were present among the follicles [31] . These changes could be attributed to the direct toxic effect of amiodarone and its metabolites [15] .…”

Prevalence of Thyroiditis and Immunohistochemistry Study Searching for a Morphologic Consensus in Morphology of Autoimmune Thyroiditis in a 4613 Autopsies Series

“…Autoimmune thyroiditis has been assumed as an age-related event associated with declining of immunity 10 and is related to the chronic use of lithium. 13,20,22 Apoptosis has also been implicated in thyroiditis pathophysiology 23 as apoptosis is detected in about 20% to 30% of epithelial cells of thyroids presenting autoimmune inflammation as compared with 1% in normal thyroid tissue. 12 Genetic background may contribute about 50% in its development and the other 50% is attributed to environmental factors.…”

“…[14][15][16] Other iodine-rich substances such as contrast media, [17][18][19] iodinated drugs, 20 and also different iodine supplementation methods 15,21 have been demonstrated to induce the development of autoantibodies and thyroid hormone changes. Autoimmune thyroiditis has been assumed as an age-related event associated with declining of immunity 10 and is related to the chronic use of lithium.…”