Thank you for your query,
The values of TSH
and Free T4 values at different intervals should be correlated with your child clinical profile and with her medication.
When she started medication like thyronine?
What is the present dose of thyroxine?
So this information is required to correlate.
Don't worry regarding this variation and your Doctor will correlate and interpret these values with your child clinical condition.
If you have any concerns please discuss with your regular doctor for clarification.
Hope i have answered your query.