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MBCHB3: Reproduction, Development and Ageing > Lecture 20: Postnatal growth > Flashcards

Lecture 20: Postnatal growth Flashcards

1
Q

What conditions are required for normal somatic growth?

A

Normal growth depends on:

  • Good general health
  • A normal hormonal milieu
  • Normal genetics
  • Adequate nutrition
  • Caring environment i.e psychosocial dwarfism
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2
Q

What are the karlberg phases of growth? and what is each stage dependent/independent on/of?

A

Infant: Rapid growth at birth declining rapidly over the first two years of life - less GH dependent

Childhood: Constant annual growth - GH dependent

Puberty: Rapid growth primarily dependent on sex steroids and increase GH release

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3
Q

Describe the proportion changes during growth:

A
  • Human beings follow a cephalo-caudal gradient of growth

- From birth to puberty the legs grow relatively faster than other post-cranial body segments

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4
Q

Write some notes on growth hormone:

A

Major anabolic hormone

  • Increases muscle mass, bone strength, linear growth in childhood
  • Decreases fat mass

Has positive effect on wellbeing.

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5
Q

What can excess GH lead to?

A

In excess, causes excess growth in childhood (gigantism) or coarsening of features in adults (acromeagly)

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6
Q

Describe growth hormone secretion, what increases and decreases its secretion?

A
  • Pulsatile with low baseline
  • Primarily at night

Increased by: Sleep, exercise stress hypoglyceamia, amino acids, malnutrition, sex steroids

Decreased by: Obesity, psychosocial deprivation, excess glucocorticoids

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7
Q

Describe the relationship between nutrition and GH/IGF1 production

A
  • Normal levels of insulin and normal nutrition are essential for normal hepatic IGF-1 production
  • Malnutrition or poorly controlled diabetes inhibit hepatic IGF-1 production. (indirect measure of GH, but must be aware of nutrition)

Insert slide of feedback

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8
Q

Insert slide 14

A

please

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9
Q

What are the growth hormones actions:

A

Metabolic

  • Inhibits glucose uptake and promotes glycogenolysis (anti-insulin)
  • Stimulates protein synthesis
  • Promotes lipolysis

Growth promoting effects
- Endocrine, paracrine and autocrine

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10
Q

Describe GH deficiency:

A
  • Abnormally slow height velocity
  • (not being short per se)
  • Increased adipocity (truncal)

In babies can have:

  • Hypoglyceamia
  • Small penis
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11
Q

What are some considerations to make when testing for growth hormone deficiency?

A
  • Random growth hormone levels are not useful
  • Best screening test is to look at height velocity
  • A normal IGF-1 makes GH deficiency unlikely
  • Formal stimulation response test can deduce GH deficiency
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12
Q

What does IGF-1 do? Where does it come from?

A
  • Major post-natal growth promotion (Majority bound to BP-3)
  • Principally produced in liver and bone
  • Insulin-like (promoting glucose, lipid and amino acid uptake) (cell proliferation and differentiation)
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13
Q

Whats the impact of estrogen on growth:

A
  • Effects on skeleton and body composition
  • Estrogen has greater effect on skeleton on than T
  • Estrogen is resp. for epiphyseal maturation/closure in both sexes.
  • In boys estrogen is responsible for bone maturation (required to fuse growth plate)
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14
Q

Describe how T3 & T4 influences growth:

A
  • Facilitatory role in growth
  • Necessary for normal GH secretion
  • Necessary for growth plate development (and body proportions)
  • Hypothyroidism causes growth failure with delay of maturation of the growth plates (delayed bone age)
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15
Q

What can cause a glucocorticoid excess and what does this cause?

A
  • Glucocorticoid excess causes cushing syndrome (multisystem disorder)
  • Exogenous steroids most common
  • Endogenous cortisol could be secreted by an adrenal tumor, or stimulated by disordered secretion of ACTH (pituitary adenoma)
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16
Q

Whats the impact of glucocorticoid excess in children:

A

Major effect on growth and body composition

  • Increased adiposity, weight and BMI
  • Slowing of growth, which may even stop
  • General features of cushing syndrome in adult generally unhelpful in children - Obese children often have abdominal adiposity, roundish face

Obesity drive growth, obese children are taller for their age.

17
Q

If the child is gaining weight but failing to grow, what should you consider

A

If the child is gaining weight, but failing to grow should be considered to have an endocrine problem i.e hypothyroidism, glucocorticoid excess, GH deficiency

18
Q

What are the important hormones of puberty?

A 
Insulin
IGF-1
Testosterone
GH
T3,4
PG E2
19
Q

How does mid-parental height est. work?

A

Boys: Dads H + Mums H (+13) / 2

Girls Dads H - 13 + Mums heigh /2

+/- 13

20
Q

Write some notes on height velocity:

A
  • HV differeniates normal variant stature from pathological short stature
  • Calc. over 6-12 months ideally
  • HV curve is shaped differently in children with delayed or early puberty
21
Q

insert HV graph ~ slide45

A

45

22
Q

What is short stature?

A
  • Symptom or a variant
  • Variant from normal growth
  • May indicate pathology
  • Normal short stature grows with normal HV
23
Q

What is bone age?

A
  • Use of x-ray atlas to use picture matching age of bones
  • Enables us to identify delayed (or advanced) bony maturation
  • Using the bone age we can predict final adult height
24
Q

What is normal variant short stature?

A
  • Familial short stature
  • Constitutional delay of growth and development
  • These 2 diagnoses account for 95% of children who present with short stature
  • HALLMARK IS NORMAL HEIGHT VELOCITY (Between 25075th percentiles
25
Q

What is pathological short stature and how can it be divided into?

A

Pathological short stature: Abnormally slow growth <25%ile suggests a growth disorder.

Proportionate or disproportionate

Early detection and treatment of underlying conditions can enable many children experiencing abnormal growth to reach their potential

26
Q

Write some notes on proportioante pathological short stature:

A

Proportionate

  • Endocrine disorders (T4 or GH deficits, or glucocorticoid excess)
  • General chronic disease
  • SGA babies
  • Syndromes
27
Q

What are the causes of disproportionate short stature:

A

Disproportioante

  • Genetic disorders
  • Cartilage or bone disorders / skeletal dysplasias
28
Q

Write some notes on SGA?

A
  • IUGR or SGA
  • Short stature by two years usually associated with short final height
  • Approx 10% become short adults.
29
Q

Write some notes on turner syndrome:

A
  • Consider in all girls with unexplained short stature
  • 50% will only have short stature as clinical feature
  • Present with short stature, poor HV or delayed puberty
  • 45XO
  • Elevated LH and FSH

MBCHB3: Reproduction, Development and Ageing (24 decks)

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