its iron. and it will be low. most babies have that. same thing happend to my son! he is 10 months now! at 9 months they gave us iron drops due to the blood test. don't worry mama! use that mommy muscle and be STRONG! he needs you to be strong for him and not worry at little things.
Im sure that there is nothing seriously wrong with your son. The doctor probably just wants to talk to you about it, good or bad. The worst that will probably happen, is he'll tell you that your son is low in a certain nutrient or something. I wouldn't stress about it too much. good luck.
