Should i be concerned if my nephew is 2 with failure to thrive, he's been this way since he was 3 months old what could be wrong?

FTT or small child?: Failure to thrive can be caused by poor oral intake, poor digestion of food, absorption or metabolism. It can also be the result of burning too many calories due to a chronic illness. You have to differentiate however true FTT from a child who is growing well below the normal curve and is just "small". Best advise is to go to a good pediatrician to get him examined and assessed.

Pediatric under-: nutrition is having a Body Mass Index less than 5th %ile. Evaluation for nutritional, medical or psychosocial causes is done by a child's pediatrician. The trajectory of growth in length, weight, head circumference & either weight-for-length or BMI differentiates a small, proportional child from one with PUN. Encourage parents to seek treatment or call CPS if you feel child neglect is an issue.