You need to get an X-ray: Lateral view of skull for nasopharynx, which would confirm the enlarged adenoids. If the tonsills are also large, or if the child is getting more than 4-5 episodes of severe tonsillitis a year, they may also need to be removed. No age is too small or too big if the correct indications are there. Normally the incidence of upper respiratory infections decreases as the size of the adenoids decrease with age, and if borderline, you may want to wait and watch.