Introduction: T hyrotoxic periodic paralysis (TPP) is a rare condition, which is mostly found in east Asian, male people and it manifests through acute onset pa-ralysis associated with sever hypokalemia. The chan-ges appear due to the internalization of potassium in the cells, a process which is mediated by the thyroid hormones’ activity. TPP can be associated with severe cardiovascular complications, mostly because of hypo-potassemia which determines heart rhythm abnorma-lities that can be fatal (sinusal pause, atrioventricular block, ventricular tachycardia, ventricular fibrillation) Methods: We report a case of a 36-year-old male pa-tient, without any personal or family history of car-diovascular diseases, with a history of energy drinks consumption, who presented to the hospital for a cu-taneous eruption, myalgia, which started 2 days after consuming meat from a fast-food. Physical examinati-on showed arrhythmic heart sounds, BP 160/80mmHg. The ECG showed atrial fibrillation (Afib) 80/min and the echocardiography showed mild diffuse hypokinesia of the left ventricle, with an EF 40%. The blood exam showed mild inflammation and hypochromic microcy-tic anemia. In the ER the patient received corticoste-roids due to the suspicion of food poisoning. After 30 minutes, the patient developed paralysis of the limbs and presented a syncope. The ECG revealed Afib with complete AVB, 30bpm, and the blood work showed a K of 1.2 mmol/L.

Results: In the meanwhile, the patient enters cardiac arrest due to ventricular tachycardia followed by ven-tricular fibrillation, which responded to multiple ex-ternal electrical defibrillation attempts. The thoracic CT showed a enlarged right thyroid lobe with a nodule (30.5/26/22mm) with fluid levels and a thin calcified wall. The lab exam: TSH inhibition (0.017 uIU/mL), high levels of FT4 (2.52 ng/dL) and anti-TPO antibody (>1000 IU/mL). The paralysis, hypopotassemia and thyroid changes were suggestive for the diagnosis of TPP. The treatment of the patient consisted in paren-teral potassium supplementation, beta-blockers and antithyroid drugs. After reaching euthyroid status the evolution of the patient was favorable, with quick reco-very. Consecutively, he undergone complete thyroidec-tomy and the histopathological examination revealed thyroid papillary microcarcinoma.

Conclusions: TPP represents a rare form of thyroto-xicosis, which is associated with a rapid evolution to cardiac arrest. This is the reason why proper and quick diagnosis and management of this pathology is vital. In the present case, the underlying afib at a young age, associated with the acute severe hypopotassemia was suggestive for an endocrinologic disease of the patient. The efficient collaboration between cardiologist and endocrinologist permitted a quick and efficient mana-gement of the patient.