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4/ RED > Childhood Growth > Flashcards

Childhood Growth Flashcards

1
Q

Why is it important to measure children?

A
  • measurements of growth provide a sensitive indication of health in childhood
  • growth rates are well defined in healthy children with adequate nutrition and an emotionally supportive environment
  • changes in growth rates can provide an early and sensitive pointer to health problems in children
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2
Q

How are body proportions of newborns and adolescents different?

A 
Newborns = larger head, smaller mandible, short neck, chest rounded, abdomen prominent, limbs short 
Adolescents = more growth of limbs relative to trunk
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3
Q

How can body proportions me measured?

A
  • arm span should equal height in adolescence
  • arm span is shorter than height in children
  • sitting height indicates torso, also limb development
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4
Q

What are the different names for short stature?

A
  • proportional short stature
  • short trunk dysplasia
  • short limb dysplasia
  • rhizomelic = short proximal limbs
  • mesomelic = short distal limbs
  • acromelic = affecting terminal part of limb
  • asymmetry
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5
Q

Describe growth charts

A
  • Standard UK growth charts based on height measurements of several thousand children over 10 years
  • separate charts for boys and girls
  • based on white UK children only
  • normal range 3rd-97th centile
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6
Q

What are the three components of childhood growth?

A
  • infancy component
  • childhood component
  • puberty component
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7
Q

What is the infancy component?

A
  • rapid, but rapidly decelerating growth in first 2-3 years
  • determined by nutrition
  • long term growth failure, if underfed in infancy
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8
Q

What is the childhood component?

A
  • switch from nutritional to hormonal dependence
  • growth and thyroid hormones most important
  • heigh velocity slows 2-3 years before puberty
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9
Q

What is the puberty component?

A
  • growth spurt, increased height velocity due to sex hormones (oestrogen and testosterone)
  • ends age 14-15 girls, age 16-17 boys
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10
Q

How does growth end?

A
  • growth ends with fusion of epiphyses due to influence of oestrogen in girls and boys
  • boys convert testosterone to oestrogen in fatty tissues (aromatase enzyme)
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11
Q

What is the first sign of puberty in girls and boys?

A

girls - breast development
boys
boys - testicular enlargement

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12
Q

What defines precocious puberty in boys and girls?

A 
boys = >9
girls = >8
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13
Q

What are the important determinants of growth?

A
  • parental phenotype and genotype
  • quality and duration of pregnancy
  • nutrition
  • specific system and organ integrity
  • psycho-social environment
  • growth promoting hormones and factors
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14
Q

How are parents heights used in determining if child height is normal?

A

Boys = fathers ht + (mothers height +12.5cm) /2
Girls = mothers height + (fathers height -12.5cm)/2
95% CI = mid-parental ht +/- 8.5cm

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15
Q

What is growth of the growth plate called?

A

chondrogenesis

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16
Q

How is the growth plate involved in growth disorders?

A
  • all growth disorders originate from, or affect the growth plate
  • building material needed every day - direct effect of nutrition and calcium/phosphate supply on growth rate and bone architecture
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17
Q

What are the layers of the growth plate?

A

resting
proliferative
hypertrophic
osteogenic

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18
Q

What are main regulators of growth?

A
  • nutrition
  • inflammatory cytokines, TNFalpha, IL-1beta, IL-6
  • extracellular fluid, oxygen deficiency, acidosis, toxins
19
Q

What are the 3 classifications of growth retardation?

A
  • primary growth plate abnormalities
  • secondary growth disorders
  • idiopathic short stature
20
Q

Give examples of primary growth abnormalities and the characteristics of them

A

A: Osteochondrodysplasia = skeletal dysplasia
- genetic abnormalities of cartilage and bone growth
- abnormal shape and size of the skeleton, and disproportion of the long bones, spine and head
- >350 disorders
B: Chromosomal abnormalities

21
Q

What is the major chromosomal reason of short stature in girls?

A

Turners syndrome

  • at birth oedema of the dorsal of the hands/feet and loose skin folds at nape of the neck
  • webbing of neck, low posterior hairline, small manidble, prominent ears, epicanthal folds, high arched palate, broad chest, wide nipple distance, cubitus valgus, hyperconvex fingernails
  • hypergonadotrophic hypogonadism, streak gonads
  • cardiovascular/renal malformations
  • recurrent otitis media
  • short stature
22
Q

What do girls with short stature due to turners need to be treated with?

A

exogenous growth hormone

23
Q

What are the four categories of secondary growth disorders?

A

A: malnutrition
B: chronic disease
C: intrauterine growth retardation
D: endocrine disorders e.g. GH and IGF-1 deficiency, hypothyroidism, cushing syndrome, pseudohypoparathyroidism, rickets

24
Q

What chronic diseases cause short stature?

A
  • Gastrointestinal: coeliac disease, IBD
  • Cardiovascular: congenital heart disease
  • Renal disease
  • Haematologic: chronic severe anaemia
  • Pulmonary: cystic fibrosis, bronchopulmonary dysplasia
  • Chronic inflammation and infection
  • Hypothyroidism: athyrosis/agenesis, dyshormogeneis, autoimmune, post-surgery
25
Q

Describe the regulation growth hormone secretion

A

Hypothalamus –> somatostatin, GHRH
Anterior pituitary –> GH
Liver –> IGF-1
Bone

26
Q

What are the causes of IGF-1 deficiency?

A

hypothalamic dysfunction

pituitary GH deficiency

27
Q

How is the hypothalamus involved?

A
  • GHRH cell bodies in arcuate nucleus, project to portal capillaries
  • regulated by food, sleep, steroids
  • negative feedback: SST, GH, IGF-1
  • neurotransmitters: adrenergic, cholinergic, opioids
  • other hypothalamic hormones: TRH, CRH
28
Q

What are the characteristics of congenital hypothalamic hypopituitarism?

A
  • doll like face

- short stature

29
Q

Where is GH produced?

Describe its secretion

A
  • synthesised in somatotroph cells, these account for 40-50% of the anterior pituitary
  • most abundant hormone
  • pulsatile secretion, max at night
30
Q

What actions just GH have?

A

Growth Hormone Binding Protein GHPH
Stimulates IGF-1 from the liver
Direct effect on growth plate and cortical bone
Decrease glucose use, increase lipolysis, increase muscle mass

31
Q

What stimulates GH secretion?

A 
exercise 
stress
hypoglycaemia 
fasting
high protein meals
perinatal development 
puberty
32
Q

What suppresses GH secretion?

A 
hypothyroidism 
hyperglycaemia 
high carbohydrate meals
glucocorticoid excess
aging
33
Q

What are the three classifications of IGF-1 deficiency?

A

A: GH deficiency (secondary IGFD)
- GH deficiency - hypothalamic dysfunction
- GH deficiency - pituitary GH deficiency
B: primary IGFD
- primary GH insufficiency (GH receptor, Laron syndrome)
- secondary GH insensitivity (signalling cascade, Stat-5)
- primary defects of IGF-1 synthesis
- primary defects of IGF-1 transport/clearance (ALS)
C: IGF-1 resistance
- defects of IGF-1 receptor
- post receptor defects

34
Q

Describe GH and IGF-1 signalling

A 
GH 
liver
factors
nucleus
IGF-1 transcription 
binding proteins in blood
chondrocytes 
growth via transcription
35
Q

Describe IGF-1 and its effects

A
  • small protein secreted in response to stimulation by GH
  • stimulates multiple processes of growth and metabolism
  • also regulated by nutritional status
  • mild glucose-lowering effects - IGF and insulin receptor structurally similar
36
Q

What 3 compounds does GH regulate and where are these produced?

A
  1. IGF-1 - hepatocytes
  2. ALS - hepatocytes
  3. IGFBP-3 - Kuppfer cells
37
Q

What are the characteristics of a boy with IGF-1 deficiency?

A
  • extreme short stature

- mid facial hypoplasia, lots of subcutaneous fat, small genitalia

38
Q

What are the 3 types of idiopathic short stature (ISS)?

A
  • familial short stature
  • constitutional delay of growth and puberty with normal height prediction
  • ISS with/without delated bone age (tempo of puberty) or with/without familial component
39
Q

What are the sequence variants in growth plate genes and height?

A

gain of function –> tall stature
normal sequence –> normal stature
mild polymorphisms –> low-normal stature
less severe –> isolates short stature
severe loss of function mutations –> skeletal dysplasias

40
Q

How is bone age used to assess delays in growth and puberty?

A
  • left hand X-ray
  • delayed bone age in GH deficiency
  • adnaved bone age in precocious puberty
41
Q

What is the most common form of short stature in children?

A

Constitutional delay in growth and puberty
Usually boys
“transient short stature”
“late bloomers”

42
Q

What is psychosocial short stature?

A
  • usually seen over age of 3 years
  • emotional rejection key factor, physical/sexual abuse may be associated
  • hyperphagia (hyperphagic short stature)
  • 50% show reversible GH deficiency
  • poor response to GH treatment
  • reverses when child nurtured outside the stressful environment
43
Q

Give examples of the following:

  1. Overgrowth with impaired final height
  2. Overgrowth with normal final height
  3. Overgrowth with increased final height
A
  1. Overgrowth with impaired final height
    - precocious puberty
    - congenital adrenal hyperplasia
    - McCune Albright syndrome
    - Hyperthyroidism
  2. Overgrowth with normal final height
    - Beckwith-Weidemann syndrome
    - Sotos syndrome
  3. Overgrowth with increased final height
    - androgen or oestrogen deficiency
    - oestrogen resistance
    - pituitary gigantism (GH XS)
    - Klinefelter syndrome (XXY)
    - Marfan syndrome
    - Homocystinuria
44
Q

What are the essential steps i assessment of growth disorders?

A
  1. measure the height of the child
  2. measure height of parents and determine mid-paretnal centile
  3. compare child’s height gentile with mid-parental centile
  4. re-measure child’s height after a period of time has elapsed
  5. calculare present growth velocity
    - if normal –> pathology unlikely
    - abnormally slow or rapid –> investigate further irrespective of height of patient

4/ RED (19 decks)

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