blocking antibodies

my son was born with hypothyroid and diagnosed at birth,hes been taking synthroid since hes been a week old and hes always had a high tsh level,after 21 months they tell me he has a blocking antibodie and they are not able to get the correct results to his tsh levels because of this ,they told me he may not even have hypothyroid,but has to continue on his medication until the age of 3 to be safe,my son is severly delayed can these antibodies have anything to do with the developmental delay of my son,his endocrine says this is a rare case and dosent seem to know much about it.

[AR-10]

Started a discussion in your other post with the same title.