A 14-year-old client presented to their primary care clinic for weekly-weight checks and Holter monitoring for sustained weight loss and dysfunctional eating behaviors. According to the referring provider’s notes, this client spent the summer out-of-state with a parent. The client returned home for the start of school, having lost more than 20 pounds (9.1 kg) using severe food restrictions. The primary care provider referred the client to the psychiatric team for sustained weight loss (more than six months) and severe bradycardia (less than 40 beats/minute), and severe hypotension (less than 90/50 mm Hg). Their current body mass index (BMI) is 16.6. The client mostly uses restriction, with intermittent binge eating/purging. Plan to admit to inpatient eating disorder program with weight restoration goal of 1 to 3 pounds (0.5 to 1.4 kg) per week until client achieves an improvement in cardiac symptoms and BMI of 19. Recent lab results indicate electrolyte imbalances. which findings will require follow-up?