Introduction: Furosemide is the most widely used diuretic in medical practice, mainly used in the treatment of congestive heart failure. It works by inhibiting sodium resorbtion from the thick ascending limb of the loop of Henle, respectively, in the distal tube. It provoke kaliurease, calciuria, elimination of ammonia, explaining the substrate of diuretic-induced metabolic alka-losis, the most common adverse effect of furosemide being hipokalemia. Severe hypokalemia presents a vital risk by causing the formation of arrhythmic substrate (prolongation of myocardial tissue repolarisation), respectively the occurrence of focal arrhythmic trigger action for ventricular arrhythmias.¹
Case presentation: A 41-year-old male without patho-logical history, presenting in the Cardiology Depart-ment, for a syncopal episode that occurred at home, with other complains such chest pain, palpitations, ge-neral malaise, cramps associated with intense muscular weakness. The clinical exam does not detect pathologi-cal changes. Electrocardiogram reveals sinus rhythm, diffuse subdenvelation of the ST segment, with T flatte-ning, U wave, sinus pause, QTc interval 620 ms. At 30 minutes after the presentation, the patient presents a another syncope without prodrome. The ECG reveals ventricular fibrillation which is converted with electri-cal shock to sinus rhythm, followed by administration of Xiline. Biologically is observed severe hypopotase-mia (1.8 mEq/l) with rhabdomyolysis syndrome and metabolic alkalosis. From the anamnesis patient re-ports use of 80-120mg Furosemide per day in the last 2 weeks, with the aim of weight loss and muscle definition. Under treatment with KCl on central venous catheter, potassium-sparing diuretic, betablocker, anti-arrhythmics, the patient has favorable evolution with correction of diselectrolymia, pH, and normalization of the QT interval. In evolution, there are self-limiting episodes of atrial fibrillation with spontaneous conversion to RS without other rhythm disturbances.
Case particularity: administration without medical advice of diuretic medication for weight loss and mus-cle definition. Severe hypokalemia complicated with cardio-respiratory arrest by ventricular fibrillation and episodes of atrial fibrillation. ICD therapy in secondary prevention not recommended due to a reversible cause of malignant arrhythmia.
Conclusion: Despite well-defined guidelines for the use of diuretics, they are often used without medical prescription among bodybuilders to define muscle and weight loss. However, the incidence of adverse events related to this practice remains low, with very few case-reports published in the medical literature.
References:

1. Ponto LL. Furosemide (frusemide). A pharmacoki-netic/pharmacodynamic review (Part I). Clin Pharma-cokinet. 1990 May;18(5):381–408.