SUN-518 Graves’ Disease Newly Diagnosed in the Setting of Hypokalemic Periodic Paralysis in an HIV+ Patient

Abstract

Relevance: A rare yet distinct cause of sudden onset paralysis is severe hypokalemia associated with thyrotoxicosis. This is thought to be associated with mutations in genes encoding cellular potassium channels. We report a case of acute onset paralysis with profound hypokalemia and a new diagnosis of Graves’ thyrotoxicosis in a previously asymptomatic African American, HIV+ man on highly active antiretroviral therapy (HAART) for over 8 years. Clinical case: A 49-year-old man with hypertension and HIV presented with acute paralysis of his bilateral upper and lower extremities. His initial potassium was 1.8 mEq/L (3.5-5.0). Prior to sudden onset loss of motor strength, he denied any preceding palpitations, tremor, anxiety, diaphoresis, hyper-defecation, weight loss, heat or cold intolerance, neck pain, increase in neck girth or difficulty swallowing, proptosis or other ocular symptoms. He has no family history of thyroid disease. He had an enlarged palpable thyroid without nodules and no audible bruit. There was no periorbital edema or proptosis, and no signs of dermopathy. A thyroid ultrasound showed a hyperemic and diffusely enlarged thyroid gland without nodules. Labs included a TSH of 0.007 mCU/mL (0.43-3.8), Free T4 2.1 ng/dL (0.71-1.85), Total T3 229.6 ng/dL (58-194), and thyrotropin receptor antibody 2.6 IU/L (0-1.75). The CD4+ count was 146 in 2010 with a slow gradual rise to 673 in 2019, and HIV viral load was undetectable. There were no offending medications or supplements identified. With aggressive potassium repletion, the serum potassium improved to 4.6 mEq/L and he regained normal strength within several hours. He was started on Methimazole 10mg daily and propranolol 10mg TID. At one month, the thyroid function tests normalized. Methimazole 10mg daily was continued and propranolol was tapered off. He remains euthyroid. Genetic testing is pending. Conclusions: Graves’ disease is the most common thyroid disease triggered by immune reconstitution in HIV + individuals on HAART. The incidence of thyroid disease in HIV patients on HAART is higher in women and Africans with a 1.5-2 fold increase compared with the general population [Muller et. al, Eur Thyroid J 2019;8:173-185]. Despite a higher incidence of hyperthyroidism in women, over 95% of cases of hypokalemic periodic paralysis have been reported in men, with a 10-fold higher incidence among Asians compared to Westerners. There has been one prior case report of Thyrotoxic Periodic Paralysis in an HIV + patient and this was in a Polynesian male (Brown JD et al. Hawaii Med J 2007). To our knowledge, this is the first case report of an African American HIV+ patient with this disorder. An association with mutations in the Kir2.6 gene (encodes a potassium channel, is expressed in skeletal muscle, and is transcriptionally regulated by thyroid hormone) has been proposed [Ryan et. al, Cell 2010 January 8; 140(1):88-98].