Recurrent abdominal pain in a 16-year-old girl

A 16-year-old girl was admitted with acute onset of abdominal pain associated with vomiting. There was no abdominal distension, fever, jaundice or gastrointestinal bleeding. She had two similar episodes in the preceding 6 months. On examination, there was mild tenderness in the epigastrium. Her blood sugar, renal parameters, results of liver function tests and serum amylase were normal. The blood samples collected for analysis are shown in Figure 1, Upper gastrointestinal endoscopy was unremarkable