Kwashiorkor

A 5-year old girl presents to the clinic for a well-child check. She was recently adopted from a refugee camp in Southeast Asia, and her biological family history is unknown. Her parents are concerned that she appears very thin but has a large protuberant abdomen. Temperature is 37°C (98.6°F), pulse is 90/min, respirations are 14/min and blood pressure is 110/70 mmHg. On physical exam, she appears irritable and minimally consolable by her mother. Examination reveals a distended abdomen, bilateral pitting edema, and muscle wasting. Laboratory results are significant for hypoalbuminemia, anemia, and hypophosphatemia. What is the most likely cause of edema seen in this patient’s condition?