My son has had repeated sinus infections and pink eye.  His Igg was 404 and he's a year old.  I don't know how to read this except that it was marked as "low" on his lab report.  I too, do not know how low this is and cannot find any information on PID in infants and it seems the reference range is different everywhere you look.  On our report the reference range was 533-1078.  The pediatrician referred him to a immunologist in St. Louis and we're awaiting his appointment.  I have a nephew with PID and the fact that my son is in the 0%ile on weight were both concerns he had.  My son's IGA was 25 and IGM was 52.  Any thoughts, ideas, would be greatly appreciated!