What is the possibility of getting thyroid disease in a normal 4 year old child ?

Low: Unless there is a family history of thyroid disease . Most states screen for thyroid disease at birth, ask your pediatrician to check your birth screening records at the state lab.

Not common: If there is a strong family history of thyroid disease, then it might be worthwhile checking with a blood test. In general it is uncommon for a normal four year old to just develop thyroid problems.

Thyroid: This is an unusual age but it could occur. Much higher chance in a female vs male. Higher likelihood if theres a strong family history in first-degree relatives ie mother, siblings, dad.