Childhood Growth Flashcards
(44 cards)
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
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
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
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
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
6
Q
What are the three components of childhood growth?
A
- infancy component
- childhood component
- puberty component
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
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
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
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)
11
Q
What is the first sign of puberty in girls and boys?
A
girls - breast development
boys
boys - testicular enlargement
12
Q
What defines precocious puberty in boys and girls?
A
boys = >9 girls = >8
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
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
15
Q
What is growth of the growth plate called?
A
chondrogenesis
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
17
Q
What are the layers of the growth plate?
A
resting
proliferative
hypertrophic
osteogenic
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
Describe the regulation growth hormone secretion
Hypothalamus --> somatostatin, GHRH
Anterior pituitary --> GH
Liver --> IGF-1
Bone
26
What are the causes of IGF-1 deficiency?
hypothalamic dysfunction
| pituitary GH deficiency
27
How is the hypothalamus involved?
- 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
What are the characteristics of congenital hypothalamic hypopituitarism?
- doll like face
| - short stature
29
Where is GH produced?
| Describe its secretion
- synthesised in somatotroph cells, these account for 40-50% of the anterior pituitary
- most abundant hormone
- pulsatile secretion, max at night
30
What actions just GH have?
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
What stimulates GH secretion?
```
exercise
stress
hypoglycaemia
fasting
high protein meals
perinatal development
puberty
```
32
What suppresses GH secretion?
```
hypothyroidism
hyperglycaemia
high carbohydrate meals
glucocorticoid excess
aging
```
33
What are the three classifications of IGF-1 deficiency?
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
Describe GH and IGF-1 signalling
```
GH
liver
factors
nucleus
IGF-1 transcription
binding proteins in blood
chondrocytes
growth via transcription
```
35
Describe IGF-1 and its effects
- 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
What 3 compounds does GH regulate and where are these produced?
1. IGF-1 - hepatocytes
2. ALS - hepatocytes
3. IGFBP-3 - Kuppfer cells
37
What are the characteristics of a boy with IGF-1 deficiency?
- extreme short stature
| - mid facial hypoplasia, lots of subcutaneous fat, small genitalia
38
What are the 3 types of idiopathic short stature (ISS)?
- 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
What are the sequence variants in growth plate genes and height?
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
How is bone age used to assess delays in growth and puberty?
- left hand X-ray
- delayed bone age in GH deficiency
- adnaved bone age in precocious puberty
41
What is the most common form of short stature in children?
Constitutional delay in growth and puberty
Usually boys
"transient short stature"
"late bloomers"
42
What is psychosocial short stature?
- 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
Give examples of the following:
1. Overgrowth with impaired final height
2. Overgrowth with normal final height
3. Overgrowth with increased final height
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
What are the essential steps i assessment of growth disorders?
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
