Tehran University of Medical Sciences Frontiers in Emergency Medicine 2717-3593 8 2 2024 04 12 e15 e15 Resul Çinpolat Emergency Medicine Department, Atatürk Sanatoryum Training and Research Hospital, Ankara, Turkey. Şeref Kerem Çorbacioğlu Emergency Medicine Department, Atatürk Sanatoryum Training and Research Hospital, Ankara, Turkey. Emine Emektar Emergency Medicine Department, Atatürk Sanatoryum Training and Research Hospital, Ankara, Turkey. Yunsur Çevik Emergency Medicine Department, Atatürk Sanatoryum Training and Research Hospital, Ankara, Turkey. 2023 10 16 2024 04 01 Objective: The aim of this study is determining the diagnostic value of the T-wave to R–wave amplitude ratio (T/R ratio) in the electrocardiogram (ECG) at the time of admission in terms of the diagnosis of hyperkalemia in patients who are at risk for hyperkalemia who apply to the emergency department (ED).  Methods: This cross-sectional study was conducted with patients over 18 years of age who presented to the ED and have an estimated glomerular filtration rate (eGFR) below 60ml/min/1.73m2. The patients were divided into 2 groups according to the potassium value; hyperkalemia and normokalaemia groups. T/R ratios were measured on the ECG. All measurements were made in these precordial leads; V2, V3, and VT highest (is defined as precordial lead where the T wave is measured the highest).  Results: A total of 345 patients with low eGFR were included. Hyperkalemia was detected in 115 (33.3%) of these patients, while 230 patients (66.6%) were in the normokalaemia group. T wave amplitude and T/R ratio were found to be statistically significantly increased in the hyperkalemia group in all leads (V2, V3, and VT highest). Area under the curve (AUC) values are 0.778 for T/R ratio and 0.717 for T wave amplitude.  Conclusion: The presence of increased T/R ratio in the ECG of patients with known low eGFR may be more helpful for the diagnosis of hyperkalemia than the classical hyperkalemia ECG findings. https://fem.tums.ac.ir/index.php/fem/article/view/1288 https://fem.tums.ac.ir/index.php/fem/article/download/1288/481