A 22-year-old male university student visits his physician w…

A 22-year-old male university student visits his physician with concerns over abdominal discomfort and recurring diarrhea for about 5 weeks. He explains that his manifestations are worse after breakfast, which usually consists of wheat cereal and yogurt. His physician’s differential diagnosis is between celiac disease and lactose intolerance. Which of the following pairs of laboratory tests would provide a definitive diagnosis?