My son is also 3 years old.  He is just starting to wear his Medic-Alert bracelet.  I too was concerned what info. to put on the bracelet but the staff at Medic Alert advised me I could only fit 6 words their telephone number and his identification number on the back of the pendant because it would be small to fit his wrist.  My sons’ bracelet says MEDIC ALERT on the front and ADRENAL HYPERPLASIA (SALT LOSING) ON STEROIDS with their phone number and his id. number on the back.  He hasn’t had another adrenal crisis since his first one at 10 days old and I hope this information will prove valuable should anything happen him and I am not their to explain his condition.  I’m sure you know the protocol with Medic Alert -that if your child becomes ill and someone (even an ambulance driver) phones the telephone number on the back of the bracelet all your details are held on record including the child’s GP, Consultant, address and your contact number.  Hope this helps.