Growth

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Growth Development in Adolescence
KN AGARWAL , President Healthcare Research
Association for Adolescents E mail
adolcare_at_hotmail.com
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Growth Development in Adolescence

• Succession of events in development of secondary
  sexual characteristics during puberty is
  consistent.
• There is individual variation in the age of
  onset, duration and tempo of Growth.

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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)

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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.

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Adolescent Growth Spurt

• Begins distally with enlargement of Hand and
  Feet, followed by the Arms Legs and finally by
  the Trunk and Chest.
• 2. Larynx, pharynx and lungsVoice
• 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.

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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

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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)

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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.

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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 gt 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).

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Development of genitals and pubic hair in boys-

• B. SMR Penis
  Scrotum testes Pubic hair
• 1. Preadolescent Testes
  lt4 ml none
• 2. Slight or no Enlarged
  darker scrotum scanty long (60)
• enlargement(11.3 yr) pigmented
  Testesgt4mm
• 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.

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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.

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Bone Growth- Completes in Adolescence

• Quantitatively important bone mineral accretion
  occurs-increase in bone density during SMR-2 to
  4(Cortical bone growth).
• Bone mineral density- 50 completes during first
  month of life to puberty onset 30 in puberty
  and 20 in late adolescence to adult.
• 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

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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.

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SEXUAL DIMORPHISM

• Shoulder growth in boys and hip growth in girls.
• 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.

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Sexual Dimorphism in Fat Distribution
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Growth Monitoring during Adolescence
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Assessment stages of SMR
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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..

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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 gt7cm at 50th and
  97th centile at 17 yr.
• BMI is lower in American-Indians

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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-tricepsbiceps sub scapular suprailiac in
  relation to SMR
• Waist/hip ratio gt0.8 women 0.9 men.

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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

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For comparison

• 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.

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Agarwals 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 lt1 in the
  1989-1991 data. In Chandigarh in 2002 we
  observed that 52 boys and 44 girls had BMI gt
  95th centile.

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Indian Children BMI Data
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Indian Children BMI Data
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Indian Children Ht Wt Data
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Indian Children Ht Wt Data
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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 .

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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

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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).

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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).

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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.

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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.

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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).

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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
  protein10-12g/ day), supplement given 172
  days/yr.- did not show any height gain.

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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-1996p786. Cont.

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  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.

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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?

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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-lt30 of total Kcal7 saturated/ 10
  polyunsaturated and 10 monounsaturated fat.
  Cholesterol ideally 200mg/day.

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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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THANKS

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