Type 1 Marine-Lenhart syndrome: An uncommon cause of thyrotoxicosis

ABSTRACT Marine-Lenhart syndrome (MLS) refers to the simultaneous occurrence of Graves’ disease (GD) and functional thyroid nodules. This report discusses a case of Type 1 MLS characterized by hyperthyroidism, the detection of thyroid-stimulating hormone receptor antibodies, and a noticeable right thyroid nodule in a middle-aged female. A thyroid scan displayed heightened tracer uptake in this nodule and uniformly elevated uptake throughout the rest of the thyroid gland. The patient received treatment with anti-thyroid medications, followed by radioiodine ablation, and is currently on levothyroxine replacement therapy. This case illustrates the importance of considering MLS in patients with both thyroid nodules and GD, especially when they exhibit an inadequate response to standard anti-thyroid drugs.