Lecture 23: Post Natal Growth Flashcards

1
Q

What are the factors that effect normal somatic growth in childhood

A
  1. Chronic conditions, genetic/chromosomal abnormalities
  2. Hormonal balance
  3. Adequate nutrition and non deprivation - (psychosocial dwarfism)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Can you compare the rates of growth in infancy, childhood and puberty and hormones influences this

A
  1. Infancy (-> 2yrs) : rapid rate of growth at birth which declines quickly over the first two years of life.
    - IGF-2, insulin, PDGF, EGF, FGF dependent (not rlly GH)
  2. Childhood - constant linear growth
    - GH, IGF-1 and T4,3 dependent,
  3. Puberty: Rapid growth primarily dependent on
    - Sex steroid, Insulin, GH, T4,3 IGF-1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does the proportion of the body change from embryo to puberty

A
  • Cephalo-> caudal gradient of growth

where embryo goes from 1/2 head to 1/8th head and 1/2 legs in puberty this is because from birth the legs grow relatively faster than other post cranial body segments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the effect of Growth hormone (anabolic), when is it secreted

Too much in childhood= gigantism, in adults growing plates stopped so acromegaly

A

+ effect on wellbeing. Stimulating liver to make IGF-1

  1. Inhibits glucose uptake and promotes glycogenolysis, promotes lipolysis for energy
    - Decreases fat mass
  2. Stimulates protein synthesis
    - Increases muscle mass
  3. IGF-1 stimulates receptors on prechondrocytes in the epiphyseal growth plate in long bones to differentiate and produce their own IGF-1 driving them to maturity
    - Bone strength

Pulsatile secretion at a low baseline primarily at night in stages 3-4 of sleep so mostly looks like 0.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What increases (8) and decreases (3) GH secretion

A

Increased

  • sleep,
  • exercise, stress, hypoglycaemia, malnutrition
  • amino acids, sex steroids

Decreased by
- obesity, psychosocial deprivation, excess glucocorticoids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Is GH an endocrine, paracrine or autocrine hormone?

what about IGF-1

A

GH All three:

  • Endocrine effects are the main (from pit)
  • Paracrine/Autocrine - tissues making their own is in cancer

IGF-1 is principally endocrine in the liver but paracine/autocrine in the bone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the clinical signs of GH deficiency in children

A
  • Abnormally slow height velocity- don’t have to be short
  • increased abdo adiposity
  • in babies they can have hypoglycaemia or small penis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How is GH deficiency tested for (3 steps)/ GH measured and when is it not accurate

A
  1. 1st look at height velocity:
    if above 25%ile (to 75th) there is no growth failure so hormone milieu is adequate
  2. IGF-1 levels measured: (random GH is not helpful)
    * But GH can be high even though IGF-1 production is inhibited by insulin or inadequate nutrition or insulin- opposite for obese children so not always accurate
  3. Formal testing requires stimulation test where in the clinic IV medications
    - (arginine (AA),
    - clonidine (sleepy),
    - insulin (hypoglycaemia),
    that induce GH secretion are given and peak response is measured
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Laron dwarfism

A

Defective GH receptor so GH doesn’t work in their body. They almost never get cancer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is IGF-1 (insulin like GF-1) and its role in growth compared to Insulin

A

IGF: Major post natal GF, majority bound to BP-3 binding protein.

Insulin: is faciliatory providing substrate for growth

Both
Promotes glucose, lipid, amino acid uptake for cell proliferation and differentiation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the effect of Estrogen on growth/ what happens if it isn’t there/not able to be made

A

Skeleton: Maturation and closure of epiphyseal plates in both sexes (more than T2 as T2->E2). If no estrogen then won’t stop growing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of thyroid hormones in growth what happens if it isn’t there/not able to be made

A

T3 and T4 is necessary for normal GH secretion and growth plate development.

Hypothyroidism causes growth failure - slow down and stop
with delay of maturation of growth plates (delayed bone age)

(Cretinism- developmental delay, deafness, severe short stature in babies not screened)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the role of glucocorticoid excess in children and how does it present, and the differential diagnoses

A

Glucocorticoids inhibit growth- excess = Cushings Syndrome

  • Increases adiposity, weight and BMI.
  • Slowing of growth which may stop

Obese children can look very similar but in childhood they have growth initiated faster, so gaining weight but not growing taller should be considered for endocrine problem:

glucocorticoid excess can look like hypothyroidism, GH deficiency,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is mid-parental height - how to calculate and what is the height range

Men average 13cm taller than Women

A

It is an estimate/guide to what the genetic potential of height based on parents

Average the heights of the two parents (M+D)/2 but if child is boy then add 13cm to mum, girl subtract 13cm from dad.

The mid parental height range is +/- 8cm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Height velocity, how to measure it and how is it applied

A

HV= (Difference in height between 2 measurements / time between measurements in months ) x 12.

Growth in centimetres per year

It is calculated over 6-12 month interval to reduce measurement errors,
allowing growth to be tracked over time.

Normal HV lies within the 25-75th centile. Children with delayed or early puberty have different curve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What 5 questions do you ask to investigate short stature history

A
  1. Parents heights to Calculate mid parental height and plot it on growth chart
  2. Parental Delayed puberty? menarche >14yrs, continued growth after hs for male
  3. Compare between other siblings
  4. Birth weight percentile-SGA babies: birthweight <10%ile, with 10% of the not catching up growth in first 6mo-2yrs so do not reach mid parental height
  5. Did they have delayed eruption of dentition/ shedding of deciduous teeth ? - related to growth
17
Q

What 6 key things to look for on examination for short stature in addition to plotting height, weight and HV

(What are the possible underlying conditions for pathological short stature -<25%ile HV)

A
  1. Signs of dysmorphism - congenital disorder
  2. Dysproportion (small limbs - genetic skeletal dysplasia)
  3. Signs of chronic disease
  4. Endocrine problem - height and weight not in concordance :
    - glucocorticoid excess, GH deficiency, hypothyroidism.
  5. Syndromes- eg, Turner syndrome
  6. Puberty signs now?
18
Q

What is Bone age- how is it used and what is the problems with it

A

Enables to identify children with delayed maturation by comparing the Left hand epiphyses of child (on Xray) with standard developmental atlas.

However this atlas is just one person, and there is variability between examiners so this test isn’t done more than once a year to stop multiplying errors

19
Q

What are the two Normal variant short statures : both reaching genetic potential

(normal birthweight, no chronic illness, cross percentiles in infant growth, normal childhood HV,)

and what is the difference between them : family history, bone age, late childhood HV, puberty timing and final height compared to average

A

Constitutional delay of growth and development :
- Family history of delayed puberty. HV in late childhood is slow with bone age being >1yr from CA.
They have delayed puberty but ultimately final height is normal

Familial short stature - Mid parental height is short, HV in late childhood and bone age is not delayed (>1 yr from CA), puberty is on time and final height is shorter

20
Q

What is Turners syndrome and how does it present

A

Girls with 45XO karyotype, high FSH, LH.

-Common feature is unexplained short stature or short for Mid parental height.

50% of them will only have short stature.

  • Also present with poor HV or delayed puberty,

neck webbing, wide spaced nipples, increased carrying angle, hand and foot oedema as infant, CVS, renal, GU problems.