Nutrition support in surgical patients

Four days after admission to the hospital for anorexia nervosa, a 20-year-old woman has new-onset palpitations and paresthesias in all four limbs. Prior to admission, she was found unconscious by her parents on the floor of a residential treatment center. The patient was started on a trial of nutritional rehabilitation upon arrival to the hospital. Her temperature is 36°C (96.8°F), pulse is 47/min, and blood pressure is 90/60 mmHg. She is 160 cm tall and weighs 35 kg; BMI is 14 kg/m2. The patient appears emaciated. Examination shows lower leg edema. A 2/6 holosystolic murmur is heard over the 5th intercostal space at the midclavicular line. An ECG shows intermittent supraventricular tachycardia and QTc prolongation. Serum studies show: Day 2 Day 4 Potassium (mEq/L) 3.5 2.7 Calcium (mg/dL) 8.5 7.8 Magnesium (mEq/L) 1.2 0.5 Phosphorus (mg/dL) 3.6 1.5 Which of the following is the most likely underlying cause of this patient's condition?

A 34-year-old man comes to the physician because of foul-smelling diarrhea, fatigue, and bloating for 6 months. During this time, he has had a 5-kg (11-lb) weight loss without a change in diet. He has type 1 diabetes mellitus that is well-controlled with insulin. Examination shows conjunctival pallor and inflammation of the corners of the mouth. The abdomen is soft, and there is diffuse tenderness to palpation with no guarding or rebound. His hemoglobin concentration is 10.4 g/dL. The patient undergoes upper endoscopy. A photomicrograph of tissue from an intestinal biopsy is shown. Which of the following is most likely to improve this patient's symptoms?