<prompt> A 12 year old girl has history of recurrent bulky stolls and abdominal pain since 3 year of age. She has moderate pallor and her weight and height are below the 3d percentile. Which of the following is the most appropriate investigation to make a specific diagnosis?Small intestinal biopsyBarium studies24-hr- fecal fat estimationUrinary d-xylose test  <response>: Answer is A Small intestinal biopsy: Small intestinal mucosal biopsy is essential in the evaluation of a patient with documented steatorrhea or chronic diarrhea 3 weeks. -- Harrisons Failure to thrive in the background of recurrent bulky stools and abdominal pain suggests a diagnosis of chronic malabsorption. Although all options provided in the question may be used to suppo the diagnosis, the most appropriate investigation to make a specific diagnosis is small intestinal biopsy. 