Exjade is recommended at a dose of 30 mg/kg body weight for normal chelation. 20 mg/kg is considered a maintenance dose for patients whose iron is under control. However, the child is quite young so a full dose may not yet be desired because of drug side effects. Since he has been on that dose for a few months, as long as he has had no serious reactions, it would be safe to double the dose for a few months. If that dose seems suitable after a few months and the ferritin continues to rise, you should again consider raising the dose by 100 mg to 300 mg daily. Your eventual goal should be 30 mg/kg but with young children it's acceptable to slowly raise the dose to the desired level so that side effects are kept to a minimum.