This document discusses failure to thrive in children. It defines failure to thrive as inadequate growth or inability to maintain growth in early childhood. It notes that failure to thrive can be organic or non-organic. Two common organic causes discussed are celiac disease and pyloric stenosis. Celiac disease causes malabsorption due to damage to the small intestine from gluten. Pyloric stenosis causes failure to thrive due to a narrowing of the pylorus which prevents food from exiting the stomach.