Objective: High iodine load in vulnerable populations, including the elderly, increases the risk of iodine-induced thyroid dysfunction. We report a case of an elderly patient presented with the Marine-Lenhart syndrome, defined as the coexistence of Graves’ disease and autonomous thyroid nodule(s) that result in biochemical hyperthyroidism. In the present case the thyrotoxic state occurred following a chest CT angiogram.

Methods: Clinical, laboratory, and radiographic data are presented as well as a review of the literature.

Results: A 73 y male has been euthyroid until after a chest CT angiogram. He presented to the endocrine service with thyrotoxic symptoms, including palpitation and weight loss. Suppressed TSH and elevated free T4 were found six weeks after the angiogram with a positive thyroid-stimulating immunoglobulin. A thyroid ultrasound examination revealed a solid nodule in the medial right lobe where a hot nodule was found on I-123 thyroid scan
with a highly elevated 24-hour uptake. He received radioiodine therapy after 2 months of treatment of methimazole.

Conclusion: This case demonstrates the occurrence of Marine-Lenhart syndrome in an older man, likely due to exposure to an excess iodine load. As the elderly represent a group at increased risk of iodine-induced thyroid dysfunction, it is advised to monitor serum thyroid function following the administration of iodinated contrast media in older individuals.