Transcript 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 :
[email protected]
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 girlsSexual 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
• separation(11.6 yr)
darker, more and curly + (92%)
• 4. Areola and papilla form secondary
• mound (13.6 yr)
coarse curly
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.
2.
3.
4.
Adrenarche is the ONSET & CONTINUITY of male
PUBERTY
Testosterone/dihydrotestosterone are needed in large
concentration to initiate “GH” via the androgen
receptors. (Thus later than girls by 1-2 yr).
Initiation testicular volume > 4 ml; maximum growth
“PHV” (10-11 cm /year) attained at Testicular volume
10-12 ml. (During SMR- G 3-4).
Testosterone –Deepens the voice and increases body
muscle mass (lean body mass).
Development of genitals and pubic
hair in boysB. SMR
Penis
Scrotum & testes
Pubic hair
1.
2.
Preadolescent
Testes <4 ml
Slight or no
Enlarged darker scrotum
enlargement(11.3 yr) pigmented Testes>4mm
3.
Longer (12.8 yr)
4.
Testes 6-8 ml
Larger, glans +
Testes 10-12 ml
breadth increased
scrotum dark
(14.1 yr)
5.
Adult size
Testes 12 ml
none
scanty long (60%)
dark, small, curling +(97%)
resemble adult type but less in
quantity and curls(99%)
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 & 2426cm 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
18
16
Triceps
14
Subscapular
Girls
12
SFT(mm)
Boys
10
Triceps
8
Subscapular
6
4
2
0
0
5
10
Age (Years)
15
20
Growth Monitoring during Adolescence
Assessment stages of SMR
Somatic growth
1. Caineo et al 2004; Ann Hum Biol. p-182growth 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 –199899 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)
30.00
adOlCARE
28.00
95th
26.00
85th
24.00
75th
BMI (Kg/m^2)
22.00
50th
20.00
18.00
16.00
14.00
12.00
10.00
0
5
10
AGE
15
20
Indian Children – BMI Data
PERCENTILES FOR BODY M ASS INDEX (BM I)
(GIRLS 2-17 YEARS)
30.00
adOlCARE
28.00
95th
26.00
BMI (Kg/m^2)
24.00
85th
75th
22.00
50th
20.00
25th
18.00
10th
5th
16.00
14.00
12.00
10.00
0
2
4
6
8
10
AGE
12
14
16
18
20
Indian Children Ht & Wt Data
PERCENTILES FOR HEIGHT AND WEIGHT
(BOYS 2-18 YEARS)
adOlCARE
200
97t h
90t h
75t h
50t h
25t h
10 t h
3rd
180
HEIGHT (cm )
160
140
120
100
97t h
80
WEIGHT(kg)
80
90t h
75t h
50t h
60
60
25t h
10 t h
3rd
40
40
20
0
0
2
4
6
8
10
A GE
12
14
16
18
20
Indian Children Ht & Wt Data
PERCENTILES FOR HEIGHT AND WEIGHT
(GIRLS 2-17 YEARS)
adOlCARE
97t h
180
90t h
75t h
50t h
25t h
10 t h
3rd
160
HEIGHT (cm )
140
120
100
80
80
97t h
60
90t h
WEIGHT (kg)
60
75t h
50t h
40
25t h
10 t h
40
3rd
20
0
0
2
4
6
8
10
AGE
12
14
16
18
Puberty – in Undernourished
.
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 .
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,CKMB 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 functionsundernourished 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 signsundernourished
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 functionsundernourished 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
studiesFrontal 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).
LESSONS IN THIS AGE GROUP:
• 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 & protein1012g/ day), supplement given 172 days/yr.- did
not show any height gain.
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, strokeand 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.
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 needsIn 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.
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