childhood growth

Question 1

what are the body proportions of a newborn baby

Answer 1

larger head, smaller mandible, short neck, rounded chest, prominent abdomen, and short limbs

Question 2

when does the fastest growth rate take place

Answer 2

fastest growth rates are in utero and infancy, gradually decreasing in rate to puberty before the pubertal growth spurt

the first 2-3 years of life, growth rate is at its fastest post natal

This growth is rapid, but rapidly decelerating

The main determinant of growth in the infancy component is nutrition, and if a child is under-fed in infancy it will lead to long-term growth failure

Growth ends with fusion of the epiphyses due to influence of oestrogen in girls and boys

Boys convert testosterone to oestrogen in fatty tissue by aromatase enzyme

Question 3

determinants of growth

Answer 3

Parental genotype and phenotype

Quality and duration of pregnancy

Nutrition

Specific system and organ integrity

Psycho-social environment

Growth promoting hormones and factors

Question 4

regulators of growth

Answer 4

Endocrine signals like growth hormones

Inflammatory cytokines

Extracellular fluid

Question 5

3 classifications of growth retardation

Answer 5

1. Primary growth plate abnormalities
2. Secondary growth disorders
3. Short statue

Question 6

2 forms of primary growth plate abnormalities

Answer 6

osteochondroplasias and chromosomal abnormalities

Osteochrondroplasias are genetic abnormalities of cartilage and bone growth
They cause abnormal shape and size of skeleton and disproportion of the long bones, spine and head

chromosomal: Turners syndrome
cardiovascular malformation, oedema of doors hands and feet at birth and loose skin on neck
webbing of neck, low posterior hairline, small mandible, prominent ears, broad chest, horseshoe kidney

Question 7

4 groups of secondary growth disorders

Answer 7

1. Malnutrition
2. Chronic disease = can lead to short stature and includes GI disorders, cardiovascular disease, renal disease, anaemia, pulmonary and chronic inflammation
3. Intrauterine growth retardation
4. Endocrine disorders = growth hormone and IGF-1 deficiency, hypothyroidism, cushings syndrome, pseudohypoparathyroidism, rickets

Question 8

IGF-1 deficiency

Answer 8

GHRH from the hypothalamus acts on the pituitary to produce growth hormone which has direct effects on growth plates

Also has indirect effects by producing IGF-1 on the liver

There is negative feedback of production of GNRH via somatostatin, IGF-1 and growth hormone

Question 9

secondary IGF-1 deficiency

Answer 9

deficiency in GH. This can be due to hypothalamic or pituitary dysfunction, but can be treated by giving exogenous GH

Congenital hypothalamic hypopituitarism will cause children to look too young for their age which can be described as a doll-like face with short stature

Growth hormone deficiency due to the pituitary will cause a similar appearance. There will be an increase in subcutaneous fat and a decrease in muscle mass