Can and toddler have hyperthyroidism

My 24 month toddler has not been gaining weight for the last year he is below the growth curve. The doctor suggested to do some analysis to check if there are issues, from his blood test he had elevated level of TSH with normal levels of free T4 lower than normal levels of creatinine and elevated eosinophila.  He has eczema since he was 3 months old and we have had issues controlling it. There are some food allergies but I don't think we have found them all. He does not see to have the symptoms described for hyperthyroidism expect for the poor weight gain and growth. He is overall happy boy but very shy. We do know of anyone in family who have hyperthyroidism but we are investigating a bit more. Can anyone suggest what could be potential diagnosis and treatment plan. I am also pregnant with my second child and I would like to avoid similar issues so any advice on prevention would also be helpful.
Thank you!

[Mark Lupo, M.D.]

an elvated TSH is consistent with hypOthyroidism -- would consider consultation w/ a pediatric endocrinologist.  The elevated eosinophils are likely due to allergies (but if there is a hypothyroidism - screen for adrenal insufficiency).