Q. A 12-year-old boy is brought to the physician’s office by her mother for fatigue, weight loss, and anorexia for the past 2 months. The boy says that he feels nauseous most of the time but he craves salty crackers. He has lost 2 kgs of weight in the past 2 months. He doesn’t have a fever, cough, or abdominal pain. His temperature is 98.6°F (37°C), pulse is 96/min, blood pressure is 100/70 mmHg, and respirations are 14/min. On physical examination, he looks poorly nourished and below the 10 percentile in weight and height. Skin and mucous membranes are diffusely dark brown, especially over the face, fingertips, toe tips, and gingiva. The rest of the examination is unremarkable. Laboratory investigations are shown below. What is the best next step in this patient’s management based on his clinical features and lab findings?