Does Marine Lenhart Syndrome really exist?

Primary hyperthyroidism is the result of overproduction of thyroid hormone resulting in the classic symptoms of tachycardia, weight loss, diaphoresis, and hyperdefecation. There are multiple common causes to include Graves’ disease, toxic multinodular goiter, and solitary toxic adenomas. Marine Lenhart Syndrome (MLS) is a rare cause of hyperthyroidism, caused by a coexistence of constitutively active thyroid nodules and Graves’ disease. In the original document of Marine and Lenhart, there is no distinction made between the autoimmune phenomenon of Graves’ disease and the solitary toxic nodule of Plummer’s disease. Rather they are both considered to be the manifestation of the same disease. However, in the current era of radionuclide technology, a clear distinction of MLS can be seen with diffuse uptake in the thyroid gland and focused enhancement in the toxic nodules. Therefore what was previously described as one entity is now distinct as Graves’ disease and Plummer’s disease. It is also becoming increasingly clear within the literature that there is also a new phenomenon of post-radioiodine immunogenic hyperthyroidism in patients with toxic nodules and elevated autoantibodies. Therefore in order to properly treat and manage patients, a new definition of MLS may need to be proposed.

Clinical Efficacy of A Single Dose Radioiodine Therapy for Hyperthyroidism

<p><strong>Objective</strong>: Radioiodine is a safe, cheap, and recognized permanent treatment option for patients with hyperthyroidism. Despite, the extensive use of radioiodine therapy in hyperthyroidism there is no consensus regarding the optimal dose of radioiodine. To evaluate the clinical efficacy and our clinical experience with the use of a single dose radioiodine therapy for hyperthyroidism in our institution.</p><p><strong>Methods:</strong> A total of 274 patients who received a single dose of radioactive iodine therapy for hyperthyroidism at our institution between 2007-2015 were retrospectively reviewed. Of these, 186 patients had Graves’ disease (GD), 73 patients had Plummer’s disease (PD), and 15 patients had a single toxic adenoma (STA). All patients received between 10-30mCi of oral radioiodine capsule. The efficacy of therapy was determined 3 months post-therapy using serum thyroid function test, weight and heart rate measurements. Therapy success refers to patients whose outcome was euthyroidism and hypothyroidism post-therapy and treatment failure where patients still manifested with persistent hyperthyroidism.</p><p><strong>Results:</strong> The efficacy of a single dose of radioiodine 3months post-therapy varies with the type of hyperthyroidism, 96% for Graves’s disease, 92% for Plummer’s disease and 100% in single toxic adenoma.</p><p><strong>Conclusion:</strong> Our study showed that a single dose of radioactive iodine therapy 3 months post-therapy is 96% efficient in all types of hyperthyroidism. However, we observed that patients at risk of therapy failure 3month post-therapy included, large thyroid gland prolong antithyroid drug usage and male gender.</p><p> </p>