pediatrics
Physical Growth and Sexual Maturation of Adolescents
Physical Growth in Adolescents
 10 cm can be expected in the year of peak velocity. A growth spurt in girls occurs sometime between ages of about 9½ and 13½, with the peak typically between ages 11 and 12½; the gain may reach 9 cm in the year of peak velocity ( Physical growth reference ). If Delayed Puberty , growth in height may slow considerably. If the delay is not pathologic, the adolescent growth spurt occurs later and growth catches up, with height crossing percentile lines until the child reaches a genetically determined stature. In children with true Precocious Puberty (typically defined as breast development before age 8 in girls, growth of the testicles and penis before age 9 in boys), an early growth spurt occurs at a young age and, ultimately, short stature results because of early closure of growth plates. Although precocious puberty is defined as sexual development starting before age 8 in girls or age 9 in boys, some children who develop before age 8 or 9 may be normal. Because onset of puberty is occurring at younger ages in the United States, especially in females, these traditional standards are being re-evaluated. All organ systems and the body as a whole undergo major growth during adolescence; breasts in girls and genitals and body hair in both sexes undergo the most obvious changes. Even when this process goes normally, substantial emotional adjustments are required. If the timing is atypical, particularly in a boy whose physical development is delayed or in a girl whose development occurs early, additional emotional stress is possible. Most children who grow slowly have a Secondary hypogonadism and catch up eventually. Evaluation to exclude pathologic causes and reassurance are needed. Guidance concerning nutrition, fitness, and lifestyle should be given to all adolescents, with special attention paid to the role of activities such as sports, the arts, social activities, and community service in the adolescent’s life. Relative requirements for protein and energy (g or kcal/kg body weight) decline progressively from the end of infancy through adolescence (see table), although absolute requirements increase. Protein requirements for boys age 15 to 18 years are 0.9 g/kg/day and for girls of the same age are 0.8 g/kg/day; mean relative energy requirements for boys age 15 to 18 years are 45.5 kcal/kg and for girls of the same age are 40 kcal/kg. 1.Tanner JM, Davies PS: Clinical longitudinal standards for height and height velocity for North American children.J Pediatr107(3):317–329, 1985. doi: 10.1016/s0022-3476(85)80501-1 