My Grandson Was Born With Congenital Hypothyroidism On 10/5/15. He

My grandson was born with congenital hypothyroidism on 10/5/15. He has been doing well , taking his thyroid med crushed and added to a small amount of breast milk. However, now has started some solids and my daughter gave med with food. April labs were abnormal, TSH was 10, I believe. His medication was increased and labs will be rechecked in 2 weeks. My question is are fluctuations in labs to be expected with normal growth and development? Is the elevated TSH in April due to administering the med with food (. I believe med was given with iron-fortified cereal)