A pediatric patient is a person who receives medical care under the age of 18, although there are some exceptions to this. For example, while most pediatricians will care for kids until they are 18 years of age, there are some who will continue to see young patients up until the age of 21. Furthermore, individuals with complex medical issues may stay with their pediatrician longer because the doctor is familiar with their needs and can provide them with the best quality of care.