Marine-Lenhart Syndrome: A Rare Cause Of Hyperthyroidism

Marine-Lenhart syndrome is a rare cause of hyperthyroidism, characterized by the coexistence of Graves' disease and a functioning nodule or toxic multinodular goiter. An 88-year-old female was admitted to the emergency department with dyspnea, lower limbs' edema, diarrhea, dysphonia and heat intolerance. During physical examination a multinodular goiter was identified. Blood tests showed elevated NT-proBNP, suppressed TSH, elevated free T4 and free T3 and positive TSH receptor antibodies. Electrocardiogram revealed new-onset atrial fibrillation. Diagnosis of acute heart failure in a patient with de novo atrial fibrillation and hyperthyroidism was assumed and specific treatment was initiated. Thyroid ultrasound showed a multinodular enlarged gland and technetium-99m (Tc-99m) scintigraphy showed hyper and hypofunctioning nodules, suggesting the diagnosis of Marine-Lenhart syndrome. Although autoimmune tests and thyroid ultrasound pattern confirm the etiology of most of Graves' diseases, scintigraphy may be useful in multinodular goiter cases, because it changes the therapeutic approach.