Growth in childhood

Question 1

Centile charts: identify how to measure height and plot centile charts, and explain the difference between height velocity and cumulative height

Answer 1

Accurate measurement is really important because abnormal growth is related to higher morbidity and mortality

Centile Charts

Height centiles express jow many people in the population are at a particular height at any age

Head measurements: reflects brain development (their bones haven’t fused yet)

Height velocity chart: cm/year

Height velocity calculation: height now -

• The “Red Book” is the book that documents child growth.
• Centile charts tell you:
  
  • Height, weight, head circumference, BMI.
  • Based on surveys of large groups of children.
  • Age (x-axis) against height (y-axis).
• 25% of children will be shorter than the 25^th centile and 75% will be taller.
  
  • Note – 50% of the population will be shorter than average (50^th centile).

•Centiles are not a “normal range”

–you can be taller or shorter than the centile lines and still be completely normal and healthy.

• Most children set out on a centile by about 2 years and grow on the same centile during childhood.
• Pattern of growth is more important than position on the centiles.

–Most very tall or very short people are healthy and grow in a normal pattern (short parents might affect: mid parental height)

•A child who falls significantly in centile position is not growing normally, whatever their height.

Question 2

Normal growth: define what constitutes a normal growth pattern and explain common causes of abnormal growth

Answer 2

Phases of growth:

1. Antenatal
2. Infancy: rapid initial growth, a continuation of fetal growth, nutritionally dependent
3. Childhood: post infancy to adolescence, growth rates in both sexes are similar, GH/ IGF-1 axis drives growth, nutrition: less impact
4. Puberty

The final part of development occurs in the spine

• Bone age: bone maturity (bone forms from cartilage which ossifies - growth hormone activates osteoblasts)

Question 3

Explain the difference between height velocity and cumulative height

Question 4

Hormonal control: list the hormonal control of growth and factors that can influence growth patterns

Obesity: define the main factors linked to increasing obesity and explain why this is a concern

Answer 4

Growth

• Normal growth can be influenced by (causes variations in growth in the population):
  
  • Events before birth – i.e. poor foetal growth, LBW, etc.
  • Medical issues in childhood – i.e. malnutrition, chronic disease.
  • Genetic factors.
  • Randomness – presence of multiple genes and the environment.
• The fastest phase of growth is between the ages of 0-2 years old – children move up and down through the centiles around this time but will move to a centile position by about 2-3 years old.
  
  • There is another phase of fast growth at puberty.
  • The skeleton matures as the child grows, the epiphyses fuse at the end of puberty and growth stops.
• Monitoring height growth:
  
  • Use of the “Red Book” – concerns should invoke the use of the red book for at least a year.
  • Timing of puberty can impact on height – late developers can fall behind in height.

Hormonal Control of Growth

• GH is the most important hormonal growth factor.
• GH secretion:
  
  • Stimulated by GnRH – pulsatile release mainly overnight.
  • Inhibited by SS.
• Effects of GH:
  
  • Some direct effects.
  • Secretion of IGF-1 from liver – then directly influences growth.

Question 5

Explain the common causes of abnormal growth

Answer 5

Causes of short stature

1. Genetic
2. Pubertal and growth delay
3. IUGR/SGA
4. Dysmorphic syndromes - Turner’s, Down’s, skeletal dysplasia (Achondroplasia)
5. Endocrine disorders - Hypothyroidism, GH deficiency
6. Chronic pediatric disease - a disease with chronic with inflammation - inflammatory mediators attach to cells and disrupt the GH from binding to cells
   
   1. Asthma
   2. Sickle cell
   3. Juvenile chronic arthritis
   4. IBS
   5. CF, CKD, CHR
7. Psychosocial deprivation

• Most short children have a normal growth pattern and do not have any medical problems.
• They are usually the children of short parents
• Not all children with intrauterine growth restriction catch up completely. Growth will be normal in childhood but they have “lost” some height in the antenatal period.
• Treatment is limited and GH hormone replacement can work when appropriate (not for “short” children).

Causes of tall stature

• tall parents
• early puberty
• syndromes eg Marfans
• growth hormone excess

Genetics of weight

• Polygenic inheritance
• Weight highly heritable trait (40-70%)
• Mongenic obesity syndromes –rare
  
  • Leptin deficiency
  • Leptin receptor deficiency
  • POMC deficiency
  • PC-1 deficiency
  • MC4R deficiency

Question 6

Obesity: define the main factors linked to increasing obesity and explain why this is a concern

Answer 6

• Definitions:
  
  • Adults – BMI of >25kg/m² is overweight, >30kg/m² is obese.
  • Children – BMI centile position – children have a lower BMI than adults that changes with age.
• Obesity figures:
  
  • Rates of obesity are increasing.
  • Some nations/cultures have higher rates of obesity.
  • Some nations/cultures tolerate obesity more.
• Complications of obesity:
  
  • More likely to get CVS disease – i.e. T2 DM.
• Why people get obese:
  
  • Intake vs. expenditure.
  • Very few people have deficiencies in leptin.
  • There are some gene variants (i.e. in FTO gene) that affect behavior and appetite.

Barker’s hypothesis: predisposition of conditions such as high cholesterol, high BP, DM, if they were born with low weight or overweight

Complications of obesity and associated features

• Type 2 diabetes
• Orthopaedic problems
• Polycystic ovarian disease
• Cardiovascular risk
• psychological problems
• Cancer
• Respiratory difficulties