Lecture 23: Postnatal growth Flashcards
(32 cards)
Normal growth during childhood depends on a combination of…
1) Good general health
2) Normal nutiriton and genetics
3) Adequate nutrition
4) Caring environment
What are the categories of disorders that can cause abnormal growth?
1) Genetic
2) Endocrine
3) Cartilage or bone disorders
4) General chronic disease
Describe Karlberg’s phases of growth
Infant
- Rapid growting at birth
- Declines rapidly over the first 2 years of life
- Less GH dependent
Childhood
- Constant annual growth.
- GH dependent
Puberty
- Rapid growth primarily dependent on sex steroids and i_ncreased GH release_
Describe the Proportion changes in a baby
- Human beings follow a cephalo-caudal gradient of growth
- From birth to puberty, the legs grow relatively faster than other post-cranial body segments
What is the Mid-parental height?
- An estimate/guide to height potential based solely on parents height
- For boys
- [Dad’s height + (Mum’s height +13cm)]/2
- For girls
- [(Dad’s height - 13cm) + Mum’s height]/2
- Mid parently height range is +/- 8cm
Describe Height velocity *
- HV differenitates normal variant short stature from pathological short stature
- HV ideally calculated over 6-12 month interval (reduce measurement errors)
- “Normal” HV lies within the 25-75th centile
- HV tracks over time
- The HV curve is shaped differently in chidlren with delayed or early puberty
- Cm/year ~ Age
- The green line reaches puberty later (normal variant)
- The red line reaches puberty earlier (normal variant)
- Girls and boys chart are different, girls go into puberty earlier and it doesn’t go for as long as the boys.
What does a short stature indicate?
- A common clinical presentation
- A symptom or a variant and not a disease
- May represent a variant of normal growth
- Normal short stature still grows with normal HV
- May indicate pathology
- One of the commonest manifestation of chronic illness; recognised or unrecognised
If a child comes in with Short Stature, what history should you take?
1) Mother and father heights
- For boys
- [Dad’s height + (Mum’s height +13cm)]/2
- For girls
- [(Dad’s height - 13cm) + Mum’s height]/2
- Mid Parental Height Range +/- 8cm
2) Family History of delayed puberty;
- menarche >14 years in females
- c_ontinued growth_ after high school in males
3) Look at other sibling’s child development records
4) Look for smyptoms of u_nderlying illness_
What are 3 signs of a growth disorder?
Signs
1) Poor height veolicty: Usually patholgoical
2) Proportionate : more likely to be a endocrine problem
3) Disproprotionate
What is a bone age?
- (relatively inaccurate) Way of assessing a child’s skeletal maturity
- Picture matching
- Allows estimate for final Height prediction
- Predicted adult height (PAH) from bone age
- Identifies your true “biological age”
- Good to compare with actual age.
- If you have a higher bone age than your actual age, you will be short.
- If you have a lower bone age than your actual age, you have growth potential.
- I_mprecise picture matching_
- Approximately 1 year intervals
- Tables of Bayley and Pinneau for final height prediction
- Predicted adult height (PAH) useful to distinguish Familial short stature and Constitutional delay in growth and d_evelopment for diagnosis_ and reassurance.
What is a Normal Variant Short Stature
- Accounts for >95% of children who present with short stature
- Hallmark is normal height velocity
2 Types:
- Familial short stature (FSS)
- Constituitonal delay of growth and development (CDGD)
What is the difference between Familial Short Stature and Chronological Growth Delay
Normal Variant Short Stature
1) Both have normal birthweight
2) Both do not have chronic illness
3) Both havea family history of short stature
4) Infant grwoth is in the X centile
5) Childhood HV is normal
6) Late childhood HV is normal in FSS but slow in CDGD
7) Bone age is the same in FSS but delayed in CDGD
8 Puberty will be less than 1 year from Chronological age in FSS but more thna 1 year from CA in CDGD
9) Puberty will be on time for FSS, Delayed for CDGD
10) Final height will be short for FSS, Normal for CDGD
Describe the pattern of Growth Hormone secretion
What is it’s release increased and decreased by?
- Pulsatile with low baseline
- Primarily at night (stages III-IV sleep)
- Increased by
- Sleep, exercsie stress, hypoglycaemia, aminoacids, malnutrition, sex steroids
- Decreased by
- Obesity, psychosocial deprivation
What causes the release of Grwoth Hormones and what does it do?
Hypothalamus releases GHRH and the pituitary releases GH
1) Inhibit uptake of glucose (promote gylcogeneolysis)
2) Increase protein synthesis
3) Increase lipolysis
GH causes the release of FFA (adipose), IGF-1 (liver) and Ghrelin (stomach)
What are the growth hormone actions?
1) Metabolic
- I_nhibits glucose uptake_ and promotes glycogenolysis (anti-insulin).
- Stimualtes protein synthesis
- Promotes lipolysis
2) Growth promoting
- Endocrine
- Paracrine
- Autocrine
(mainly effect on the growth plates (e.g. epiphyseal growth plate)
Describe Laron Dwarfism
GH Receptor defect
Describe IGF-1
- Insulin-like growth factor 1 (IGF-1), also called somatomedin C
- Major post-natal growth promoting factor
- Majority bound to binding proteins
- Principally produced in liver (endocrine) and bone (paracrine, autocrine)
-
Insulin-like (promoting glucose, lipid and amino acid uptake)
- Cell proliferation
- Cell differentiation
Describe the features of IGF binding proteins
Almost all circulating IGF are bound to IGFBPs
IGFBP-3 is the most common, GH dependent and binds IGF-1
Describe the role of estrogen on growth
Estrogen has effects on skeleton and b_ody compositio_n
Estrogen has greater effect than testosterone on skeleton
Estrogen is responsible for epiphyseal maturation/closure in boths sexes
What would you observe in a male with a mutation that prevents estrogen production?
Grwoth plates don’t fuse and growth does not stop
Describe the features of hypothyroidism
Severe short stature
Developmental delay
Deafness
“creatinism”
Describe the role of T3 and T4 on growth
They have a facilitatory role in growth
Necessary for normal GH secretion
Necessary for growth palte development (and body proportions)
Describe the role of insulin in growth
Facilitatory role in growth
Provides substrate for growth (amino acid uptake, gylcogenesis and lipogenesis)
What growth hormones are important in different stages of a person’s life?
Foetus:
1) IGF02
2) INsulin
Child
1) GH
2) IGF-1
3) T4/T3
Puberty
1) GH
2) Estrogen
3) IGF-1
4) Insulin
5) TF/T3
