A 58-year-old, previously healthy man is evaluated due to a 2-month history of early satiety, postprandial epigastric pain and vomiting, and unintended weight loss. Physical examination shows cachexia and a palpable epigastric mass. Upper gastrointestinal endoscopy reveals a large prepyloric mass causing gastric outlet obstruction; biopsy of the mass is consistent with poorly differentiated adenocarcinoma. Abdominal CT scan reveals thickening of the gastric wall with adjacent fat infiltration, enlarged lymph nodes, and multiple hepatic metastatic lesions. The disease is considered unresectable, and the patient undergoes laparoscopic gastrojejunostomy for palliation of gastric outlet obstruction. Postoperatively, he tolerates tube feeding but experiences worsening weakness. The patient also has frequent episodes of nonsustained ventricular tachycardia. Laboratory results are as follows: Which of the following is the most likely cause of this patient's worsening condition?

Question

A 58-year-old, previously healthy man is evaluated due to a 2-month history of early satiety, postprandial epigastric pain and vomiting, and unintended weight loss.  Physical examination shows cachexia and a palpable epigastric mass.  Upper gastrointestinal endoscopy reveals a large prepyloric mass causing gastric outlet obstruction; biopsy of the mass is consistent with poorly differentiated adenocarcinoma.  Abdominal CT scan reveals thickening of the gastric wall with adjacent fat infiltration, enlarged lymph nodes, and multiple hepatic metastatic lesions.  The disease is considered unresectable, and the patient undergoes laparoscopic gastrojejunostomy for palliation of gastric outlet obstruction.  Postoperatively, he tolerates tube feeding but experiences worsening weakness.  The patient also has frequent episodes of nonsustained ventricular tachycardia.  Laboratory results are as follows:  Which of the following is the most likely cause of this patient's worsening condition?

Quizplus · Accepted Answer

This patient with a malignant gastric outlet obstruction has evidence of severe malnutrition (ie, weight loss, cachexia). The development of hypophosphatemia, hypokalemia, weakness, and arrhythmias after the initiation of tube feeding suggests refeeding syndrome, which occurs after the reintroduction of nutrition in patients with chronic malnourishment (eg, anorexia nervosa, malignancy). Starvation results in the depletion of phosphate, although serum levels may remain normal due to transcellular shifts. The reintroduction of carbohydrates (ie, tube feeding) leads to increased insulin secretion. This stimulates the cellular uptake of electrolytes (ie, phosphate, potassium, magnesium) and increases phosphate utilization during glycolysis (eg, formation of ATP, 2-3 diphosphoglycerate). This eventually leads to phosphate depletion and failure of cellular energy metabolism, as well as massive fluid and electrolyte shifts. Manifestations of refeeding syndrome include muscle weakness (which can include the muscles of respiration), arrhythmias, congestive heart failure, rhabdomyolysis, and neurologic dysfunction (eg, paresthesia, seizure). The disorder is characterized by hypophosphatemia; other common laboratory abnormalities include hypomagnesemia, hypokalemia, and liver function test abnormalities. Management includes close laboratory monitoring and aggressive repletion of electrolytes. (Choice A) Hepatic metabolic dysfunction (eg, due to massive tumor burden) results in loss of synthetic function (eg, coagulopathy, hypoalbuminemia) and ammonia accumulation (eg, asterixis, hepatic encephalopathy). Electrolyte abnormalities and arrythmias would be unexpected. (Choice B) Infection can cause leukocytosis and could induce arrythmias in a patient with underlying cardiac disease. However, this patient has no cardiac history, and infection would not cause muscle weakness or electrolyte abnormalities. (Choice C) Hypermetabolic syndrome typically occurs in the setting of severe burns, sepsis, or hyperthyroidism, not chronic malnutrition, which suppresses metabolism. It typically results in ongoing protein catabolism and weight loss despite adequate nutrition; severe electrolyte derangements and muscle weakness would be unexpected early in the clinical course. (Choice E) Paraneoplastic syndrome can cause metabolic disturbances but typically results in hyponatremia (syndrome of inappropriate antidiuretic hormone), hypercalcemia (humoral hypercalcemia of malignancy), or hypoglycemia. Hypokalemia and hypophosphatemia developing after nutritional repletion is more suggestive of refeeding syndrome. Educational objective: Refeeding syndrome occurs after the reintroduction of nutrition in patients with chronic malnourishment. Clinical manifestations include hypophosphatemia and other electrolyte abnormalities, muscle weakness, arrhythmias, and congestive heart failure.

A 58-Year-Old, Previously Healthy Man Is Evaluated Due to a 2-Month