Hannah, a 1-year-old girl, is brought to the clinic for a routine immunization by her mother. Mr. and Mrs. Rosen have a healthy 5-year-old boy at home. The pregnancy with Hannah was uneventful and a fetal ultrasound done at 16 weeks gestation was normal. The baby was born by spontaneous vaginal delivery, breathed immediately, and was placed on the breast for mom to nurse. Hannah's birth weight was 3.4 Kg. After seeming to feed normally for 24 hours, Hannah vomited bile and the abdomen was noted to be distended. An x-ray was interpreted as showing a distal small bowel obstruction. Further contrast x-rays of the colon showed a microcolon and inspissated meconium in the proximal colon, making a diagnosis of meconium ileus. Genetic testing confirmed cystic fibrosis. After a lengthy hospitalization to correct the bowel obstruction, Hannah was discharged home receiving exclusive breast milk. At 4 months of age, Hannah was switched to a cow's milk formula. Her mother noticed that she cried a lot. Hannah's mom attributed the symptoms to a milk allergy and progressed through a variety of cow's milk and soy formulae. At present Hannah is taking 1 litre of Rice milk and a small variety of foods daily. She has one small formed stool per day. She weighs 8.5 kg and is 74 cm tall.