Pathologic U Waves Secondary to Severe Hypophosphatemia During Refeeding Syndrome

A patient in their early 20s was admitted to the hospital's acute medical unit complaining of palpitations and weakness. During the previous 3 months, the patient had experienced depression and suicidal ideations. Four days prior to admission, the patient had stopped eating and drinking but had eaten a banana on the way to the hospital. Initial observations of the patient were: weight, 62 kg (7 kg less than baseline); body mass index (calculated as weight in kilograms divided by height in meters squared), 20; heart rate, 110 beats/min; blood pressure, 122/66 mm Hg; jugular venous pressure, 0 cm H2O; respiratory rate, 18 breaths/min; and oxygen saturation, 99%. An electrocardiogram (ECG) performed on admission demonstrated sinus tachycardia with inverted T waves and pathologic U waves (upward deflection >2 mm immediately after the T wave), most prominent in V2 through V4.