Pediatrics (also spelled paediatrics) is the branch of medicine that deals with the medical care of infants, children, and adolescents (from newborn to age 14-21, depending on the country).
See also:
http://en.wikipedia.org/wiki/Pediatric
Pediatric endocrinology (British: Paediatric) is a medical subspecialty dealing with variations of physical growth and sexual development in childhood, as well as diabetes and other disorders of the endocrine glands.
http://en.wikipedia.org/wiki/Pediatric_endocrinology