dear user, yes in your daughter s case treatment of hypothyroidism is necessary. Since TSH level is high (normal level 0.5-5.5). Yes hypothyroidism can slow down the growth and since your daughter is in pubertal age group which is the fastest growing period of life it is essential that her thyroid status remains normal so levothyroxine supplementation as prescribed by your doctor should be continued. Also beware about the fact that hypothyroidism can delay the pubertal changes. Since her GH level is normal and bone age is also normal she does not need GH supplementation. I hope that answers all your queries.