A 3-Year-Old Boy Is Brought to the Emergency Department by His

A 3-year-old boy is brought to the emergency department by his parents due to fatigue and refusal to eat.  His family recently arrived in the United States from Syria.  He has had watery diarrhea for the past several days but no fevers or vomiting.  His appetite has been decreased for several weeks.  Today, he has refused to eat but has drunk a few cups of water and juice.  Limited medical records show that tuberculosis skin testing was negative and catch-up vaccines were administered at the time of immigration.  Temperature is 36.1 C (97 F) , blood pressure is 100/65 mm Hg, pulse is 100/min, and respirations are 22/min.  Height is 91 cm (36 in) and weight is 12 kg (26 lb 8 oz) , corresponding to the 10th and 5th percentiles, respectively.  Physical examination shows a gaunt, tired-appearing boy.  Oral mucous membranes are dry but without ulcers or thrush.  He has bilateral pitting edema of the lower extremities, and his upper extremities have minimal subcutaneous fat.  A soft, vibratory heart murmur is heard on auscultation.  The lungs have no adventitious sounds.  The abdomen is mildly distended but otherwise soft and nontender.  Initial laboratory results are as follows: Stool occult blood test is negative.  Which of the following is the most appropriate initial step in management of this patient?

A) Begin a high-calorie oral diet
B) Begin oral rehydration solution
C) Insert an nasogastric tube and administer a high-protein diet
D) Place a central venous catheter and administer a 20-mL/kg isotonic fluid bolus
E) Place a peripherally inserted central catheter and administer total parenteral nutrition