Endocrine Abstracts

Background: Marine-Lenhart Syndrome represents a rare endocrine disorder occurring in 0.8-4.1% of Graves’ disease cases, characterized by the coexistence of Graves’ disease and autonomously functioning thyroid nodules. Marine and Lenhart in 1911, this syndrome presents unique therapeutic challenges compared to isolated Graves’ disease. This syndrome remains frequently underdiagnosed, and warrants increased clinical recognition given its distinct therapeutic implications.

Case Presentation: We report a case of a 44-year-old female presenting with thyroid goitre, diarrhoea, and unintentional weight loss. Laboratory evaluation revealed severe hyperthyroidism with suppressed thyroid-stimulating hormone (<0.01 μIU/mL), elevated free thyroxine (2.58 ng/dL), elevated free triiodothyronine (8.7 pg/mL), and elevated thyroid-stimulating immunoglobulins (0.72 IU/l). Thyroid ultrasonography demonstrated hypoechoic nodules in the right lobe, showing TR4 features, that measures 10 × 9 × 8 mm (width × height × length). Radioiodine uptake scan revealed asymmetrical in site with the right thyroid gland is functionally larger on the left lobe. There is increased uptake in the expanded interpolar region of the right lobe. There is significantly less uptake in the rest of the thyroid gland. The thyroid uptake at 20 minutes post administration is calculated 57% uptake in the right lobe with contralateral suppression, appearances are in keeping with toxic nodule in the right interpolar region. The combination of elevated thyroid-stimulating immunoglobulins and a hyperfunctioning nodule established the diagnosis of Marine-Lenhart Syndrome. Initial management with carbimazole achieved biochemical remission of the Graves’ component.

Conclusion: This case highlights the importance of comprehensive evaluation in hyperthyroid patients, including thyroid-stimulating immunoglobulin assessment and functional imaging, to identify Marine-Lenhart Syndrome and guide appropriate therapeutic decision-making.