Review Question - QID 216614

This cachectic, homeless patient with a history of alcohol abuse who develops QT prolongation in the setting of electrolyte abnormalities, after a few days with access to food in the hospital, is likely suffering from refeeding syndrome due to a sudden insulin surge in the setting of chronic malnutrition.

Refeeding syndrome is a life-threatening clinical phenomenon that can occur in patients who are severely or chronically malnourished, such as patients with anorexia nervosa, alcohol use disorder, or homelessness. In these patients, the starvation state leads to elevated serum glucagon to upregulate catabolic processes (glycogenolysis, gluconeogenesis, lipolysis, muscle breakdown) as strategies to provide energy for the body. In this state, total body stores of vitamins and ions may become low, though homeostatic mechanisms will seek to maintain normal levels. If these patients experience significant feeding or alimentation, the sudden insulin release will drive ions (especially K+, Ca2+, Mg2+, and phosphorus) intracellularly, precipitating the symptoms of those electrolyte disturbances. Phosphorus in particular is thought to be responsible for many of the symptoms, most notably arrhythmias which can be life-threatening.

Solomon et al. detail the pathophysiology of refeeding syndrome, as well as describe the sequelae of the individual ion abnormalities that can result.

Incorrect Answers:
Answer 1: Gastrointestinal losses due to malabsorption can lead to low serum K+ and HCO3-, as well as various vitamin deficiencies, which could cause arrhythmias. They are less likely to precipitate significant alterations in Ca2+ or phosphorus. Additionally, this patient has not described symptoms such as diarrhea, leading this to be an unlikely explanation of his symptoms.

Answer 2: Glucagon surge after a prolonged state of anabolism is inaccurate because this patient, who is chronically malnourished, would likely have chronic catabolism to provide his body energy. In addition, now that he is eating, he likely is experiencing an insulin surge, driving serum K+, Ca2+, and phosphorus intracellularly. By contrast, glucagon would drive these ions extracellularly and thus would lead to hyperkalemia, hypercalcemia, and hyperphosphatemia, none of which are present in this patient.

Answer 3: Glucagon surge after a prolonged state of catabolism is inaccurate because this patient has begun eating, and thus likely is experiencing an insulin surge, driving serum K+, Ca2+, and phosphorus intracellularly. Glucagon would drive these ions extracellularly, and thus would lead to hyperkalemia, hypercalcemia, and hyperphosphatemia, none of which are present in this patient.

Answer 4: Insulin surge after a prolonged state of anabolism is inaccurate because this patient, who is chronically malnourished, would likely be in a state of chronic catabolism to provide his body energy that he is not receiving from normal nutrition.

Bullet Summary:
Refeeding syndrome is a life-threatening condition characterized by a rapid intracellular shift of K+, Ca2+, and phosphorus due to a sudden insulin surge, often presenting with arrhythmia in malnourished individuals who begin eating.