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Growth & Development in Adolescence KN AGARWAL , President Healthcare & Research Association for Adolescents E mail : [email protected]
Growth & Development in Adolescence
KN AGARWAL , President
Healthcare & Research
Association for Adolescents
E mail :
Growth & Development in Adolescence
1. Succession of events in development of
secondary sexual characteristics during
puberty is consistent.
2. There is individual variation in the age of
onset, duration and tempo of Growth.
Ethnic & Sibling variability in the onset and
duration of Puberty
1. Ethnic- American Blacks enter puberty earlier than Whites: Breast Stage-2 at 8 years of age Blacks 48%(average age 8.8yr; PH- 8.7yr); Whites-only 15%(Av age 9.9yr; PH 10.7 yr). However, “Menarche” same time 12.2yr and 12.8yr, respectively.
2. Besides racial “Onset of Puberty” is different in an individual child, as well as in case of siblings (Ann Hum Biol 2005; et al Das Gupta)
Puberty encompasses- - Somatic
Growth & Sexual development
1. Adolescent growth spurt,
2. Development of secondary sexual
characteristics.
3. Attainment of fertility.
4. Establishment of individual sexual identity.
5. Timing for Puberty onset has wide variability-
6. Girls- 8-12 years and Boys- 9-14 years of
age.
Adolescent Growth Spurt
1. Begins distally with enlargement of Hand and Feet, followed by the Arms & Legs and finally by the Trunk and Chest.
2. Larynx, pharynx and lungs—Voice
3. Androgens- a) Sebaceous glands- Acne, b) Optic globe-myopia and c) dental- jaw growth, loss of deciduous teeth eruption of permanent cuspids, premolars, and finally molars.
Puberty -GIRLS
1. First sign of ovarian estradiol secretion is breast development “Thelarche”.SMR-B-2 (Breast budding)- GROWTH IN HEIGHT.
2. Estradiol is a good stimulator of “GH” it doubles the growth velocity “PEAK HEIGHT VELOCITY’(9-10 cm / yr). Coincident with B-3. Follows B-2 by 1 yr.
3. Change in body shape
4. Growth under arm hair followed by secretion
5. Menarche follows PHV by 14-18 months.
6. Adult size breast
Development of breast and pubic hair
in girls- (Indian Data)
• Development of breast and pubic hair in girls-
• Sexual maturity Breast Pubic hair (Mean age = 13.6yr)
• Stages (SMR)
• 1. Preadolescent Pre-adolescent
• 2. Bud stage and
• papilla elevated sparse lightly pigmented straight
• as small mould (10.2 yr) around medial border of labia (22%)
• 3. Areola enlarged no contour darker, more and curly + (92%)
• separation(11.6 yr)
• 4. Areola and papilla form secondary coarse curly
• mound (13.6 yr) abundant (98.8%)
Menarche & linear growth
The growth in the post menarche
period is limited as girls can gain 5-6
cm in linear growth, only.
Thus the maximum gain in height is
pre-menarche in SMR- stages –B-2
& B-3.
Puberty- BOYS
1. Adrenarche is the ONSET & CONTINUITY of male
PUBERTY
2. Testosterone/dihydrotestosterone are needed in large
concentration to initiate “GH” via the androgen
receptors. (Thus later than girls by 1-2 yr).
3. Initiation testicular volume > 4 ml; maximum growth
“PHV” (10-11 cm /year) attained at Testicular volume
10-12 ml. (During SMR- G 3-4).
4. Testosterone –Deepens the voice and increases
body muscle mass (lean body mass).
Development of genitals and pubic
hair in boys-
B. SMR Penis Scrotum & testes Pubic hair
1. Preadolescent Testes <4 ml none
2. Slight or no Enlarged darker scrotum scanty long (60%)
enlargement(11.3 yr) pigmented Testes>4mm
3. Longer (12.8 yr) Testes 6-8 ml dark, small, curling +(97%)
4. Larger, glans + Testes 10-12 ml resemble adult type but less in
breadth increased scrotum dark quantity and curls(99%)
(14.1 yr)
5. Adult size Testes 12 ml spread to medial surface of thigh
(16.4 yr)
Facial hair 14.8 yr.
Adolescent Growth Spurt
• Adolescence Growth - Period extends for
2.5 to 3 years; to cross Sexual Maturity
stages 2-5.
• Height gain is 27-29cm in boys & 24-
26cm in girls; (1 cm height will need 4500
Kcal)
• Weight gain in both 25-30 kg.
Bone Growth- Completes in
Adolescence
1. Quantitatively important bone mineral accretion occurs-increase in bone density during SMR-2 to 4(Cortical bone growth).
2. Bone mineral density- 50% completes during first month of life to puberty onset; 30% in puberty and 20% in late adolescence to adult.
3. 1 cm height gain needs Ca-20g; 30% gets absorbed (need 1300 mg/d Natl Acad. Sci. USA-97-98; AJCN 2005;-p 175). Take 4 cups of milk/d. DEFICIECY-FRACTURES
Brain Growth in Adolescence
1. Early Childhood- Maximum Brain grows as “Frontal circuits”- related to organization and planning.
2. Adolescence- Brain grows in the rear of the brain- linked more to language learning and spatial understanding. Thus brain development continues.
3. Myelination of the prefrontal cortex continues in adolescence.
SEXUAL DIMORPHISM –
1. Shoulder growth in boys and hip growth in girls.
2. They start puberty with similar fat and lean body mass content . Girls finally have 27% fat and boys 18%, from 16% . In boys gain in lean body mass is twice than the girls. But girls reduce LBM from 80% to 74%.These changes are due to sex hormones
3. Maintenance cost of lean body mass needs more energy .Thus boys have increased deposition of protein and minerals e.g. Fe/Ca/Zn. Sports- need oxygen & nutrition.
Sexual Dimorphism in Fat Distribution
0
2
4
6
8
10
12
14
16
18
0 5 10 15 20
Age (Years)
SF
T(m
m)
Boys
Girls
Subscapular
Triceps
Subscapular
Triceps
Growth Monitoring during Adolescence
Assessment stages of SMR
Somatic growth
1. Caineo et al 2004; Ann Hum Biol. p-182-
growth measured on daily basis has
Stasis, steep changes, and continous
growth period with wide individual
variation.
2. Cole et al 2000. BMI curves lost sensitivity
in puberty.
3. Already said sexual growth varies in onset
and duration- ethnic, individual & sibling..
Growth pattern- variations
• Asian children- Chinese, Japanese,
Korean, Taiwanese and Indian have
similar linear growth-max difference
1 cm at 17 yr age.
• NCHS and Europeans are taller by
>7cm at 50th and 97th centile at 17 yr.
• BMI is lower in American-Indians
How to Measure - somatic growth in
adolescence
• Assess sexual maturity.
• Ht,wt, BMI, SFT for age in relation to
Sexual Maturity.
• BMI (kg/m2)- “Adolescence”.- SMR
related -BMI.
• SFT-triceps+biceps sub scapular +
suprailiac in relation to SMR
• Waist/hip ratio >0.8 women; 0.9 men.
REGIONAL DISTRIBUTION
OF FAT • Central Obesity- Excess abdominal
fat(Android)-more associated with
hyperglycemia, hyperlipidemia, increased
triglycerides, hypertension seen more in
South Indians &South Asians
• Peripheral fat around body(Gynoid)- is
associated with less morbidity & mortality
For comparison
1. Growth data – Somatic and Sexual growth
data and the table prepared for ADOLESCENT
children; Indian Pediatr 1992 & 2001(-The
Growth-2003 CBS Publ. book) are the best
available sets on affluent Indian children.
2. Virani 2005; Ann Hum Biol-Pondicherry 40 yr
data-secular growth in 20 yr has plateaued.
Indians are shorter than Europeans.
Agarwal’s data 1989-91.
• CDC 2000, did not use the NHANES III –1998-99 data in growth curves, as obesity had significantly increased as compared to 1976-84 data.
• Agarwal et al data on affluent children was collected during 1989-1991. In 2002; 2000 boys were re-examined in Delhi by us; there was no secular trend for height, but obesity was observed in 10% as compared to <1% in the 1989-1991 data. In Chandigarh in 2002; we observed that 52% boys and 44% girls had BMI > 95th centile.
Indian Children – BMI Data PERCENTILES FOR BODY MASS INDEX (BMI)
(BOYS 2-18 YEARS)
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
26.00
28.00
30.00
0 5 10 15 20
AGE
BM
I (K
g/m
^2)
50th
75th
85th
95th
adOlCARE
Indian Children – BMI Data
PERCENTILES FOR BODY MASS INDEX (BMI)
(GIRLS 2-17 YEARS)
10.00
12.00
14.00
16.00
18.00
20.00
22.00
24.00
26.00
28.00
30.00
0 2 4 6 8 10 12 14 16 18 20
AGE
BM
I (K
g/m
^2)
5th
10th
25th
50th
75th
85th
95th
adOlCARE
Indian Children Ht & Wt Data PERCENTILES FOR HEIGHT AND WEIGHT
(BOYS 2-18 YEARS)
0
2 0
4 0
6 0
8 0
1 0 0
1 2 0
1 4 0
1 6 0
1 8 0
2 0 0
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0
AGE
adOlCARE
3 r d
10 t h
2 5 t h
5 0 t h
7 5 t h
9 0 t h
9 7 t h
3 r d
10 t h2 5 t h5 0 t h
7 5 t h
9 0 t h
9 7 t h
8 0
6 0
4 0
WEIGHT(kg)
HEIGHT (cm)
Indian Children Ht & Wt Data
PERCENTILES FOR HEIGHT AND WEIGHT
(GIRLS 2-17 YEARS)
0
2 0
4 0
6 0
8 0
1 0 0
1 2 0
1 4 0
1 6 0
1 8 0
0 2 4 6 8 1 0 1 2 1 4 1 6 1 8
AGE
adOlCARE
HEIGHT (cm)
WEIGHT (kg)
10 t h
3 r d
2 5 t h
5 0 t h
7 5 t h
9 0 t h
9 7 t h
3 r d
10 t h
2 5 t h
5 0 t h
7 5 t h
9 0 t h
9 7 t h
6 0
4 0
8 0
.
No age period could be identified for peak height velocity
Height gain was similar to affluent Indian
children in adolescent growth spurt.
• Deficit of early life in height was not corrected.
Weight gain was 38% of the affluent Indian .
Puberty – in Undernourished
Undernourished- early life to
adolescent
ICMR-1982-96 (Agarwals)
Boys had delayed maturation of:
• Genitals by 1.54 yr;
• Pubic hair by 0.82 yr and
• Axillary hair by 0.65 yr .
• Testicular vol. was similar.
• Girls had delayed breast development
by 2.19 yr.
• Menarche was delayed by 0.82 yr
Undernourished Adolescents until 17.5 yr
of age (To achieve linear growth)
• Maintain their vital functions by mobilising
amino-acids from body muscles as
demonstrated by increased serum enzyme
activities i.e. LDH, ALP, AST, ALT, CK,CK-
MB and CK-mm.
• 31- phosphorus magnetic resonance
spectroscopy showed that -ATP and Pi
were significantly increased at the cost of
Pcr (Phosphocreatinine). These changes
simulate myopathic status (Agarwals-Acta
Peditar. 1994).
Higher mental functions-
undernourished adolescents There was deficit in higher mental abilities
related to personal and current
information, orientation, mental control,
logical memory, attention span, visual
reproductive and associative learning:
impairment in overall memory function in
set formation and conditional learning
(Agarwals-Acta Paediatr 1995).
Soft neurological signs-
undernourished
adolescents
Soft neurological signs observed in
preschool years persisted affecting
repetitive speed movements more
with higher degree of overflow and
dysrythmia (Agarwals-Nutr Res
1995). Thus chronic UN affects brain
function for finger coordination.
Higher mental functions-
undernourished adolescents
Reaction time studies by Audio-visual RT
apparatus and electromyograph:-
showed affects on perceptual abilities,
information processing and analytical
capabilities (Agarwals-I J M R; 1998).
Those who became normally nourished
still had raised RT, due to early life UN.
BRAIN- MRI studies-in
undernourished Adolescent • MRI and cognitive evoked potential
studies-
Frontal lobes- Size was reduced &
Asymmetry of anterior as well as posterior lobes was less pronounced.
P3 latency was normal, but the P2 and P3 amplitudes were higher suggesting neuronal compensation.
(Agarwals-Nutr Res 1996).
• No scientific study to show that nutrition supplement will improve the peak height velocity or the total height to compensate the stunting of early life.
• N F I-study-(Agarwals- IJMR-1989;) children 6-8 yr of age followed for 2 yr (preadolescent undernourished) with (450-500 kcal & protein10-12g/ day), supplement given 172 days/yr.- did not show any height gain.
LESSONS IN THIS AGE GROUP:
Other nutrition related adolescent health
issues-
• Lesions of Atherosclerosis begin to accelerate .
• 1997-98 D. R. I.(Natl. Acad Sci, USA)-Folate 400ug/d-Prevents Atherosclerosis, clogging of arteries, heart attack, stroke-and reduce homocystein in smokersJAMA-1995 p1049-57.
• Vitamin E-10 IU, Prevents Ca-deposit in Bl. Vs; neutralizes oxidation of bad LDL cholesterol-RBC membrane antioxidant in smokers. LANCET-1996;p786. Cont.
Extremes of nutrition intake
• i) Overeating resulting in overweight and
obesity; Induce rapid growth and early bone
maturation; mestural functions; hypertension,
diabetes, hyperlipidemia etc.
• ii) for social pressure to reach cultural ideals of
thinness - excessive dieting e.g. anorexia
nervosa- 1% (more in girls) and bulimia-can lead
to renal failure, secondary amenorrhea irregular
heart rate, bone marrow hypoplasia,
osteoporosis and dental erosion.
Dieting+ Intensive physical
training for-thinness
Alters hypothalamic-pitutary axis in adolescent girls – menstural functions altered and bone density reduced.
Problems-Missing meals (girls)/reduced frequency/too much carbonated drinks, ice cream, french fries etc - low in macronutrient & micronutrients?
Energy/ Protein/ Fat
• Needs around 136500Kcal as total cost of adolescent growth spurt.Peak energy needs- In girls with budding of mammary gland(SMR II-III) in boys(SMR-III-IV); 2200 and 3000Kcal resp/d
• Protein 12-14% of energy- Boys 0.34g/cm ht. Girls 0.28g/cm ht.
• Fat-<30% of total Kcal;7% saturated/ 10% polyunsaturated and 10% monounsaturated fat. Cholesterol ideally 200mg/day.
Cont.-Natl. Acad Sci USA-1997-98
• Recommends-B-complex group
:Pyridoxine1.3mg, Riboflavin 1.3mg,
Niacin 16mg,Thiamin 1.2mg folate 400ug
pantothenic acid 5.0mg, Biotin 25ug,
Choline 550mg, --Important for cellular
energy metabolism
• Vitamin C-Collagen synthesis
• Vitamin D for Ca absorption.
