Pediatric Growth and Development Flashcards

1
Q

during growth plate growth, chondrocytes start in the ____ zone and migrate towards the ____

A

during growth plate growth, chondrocytes start in the GERMINAL zone and migrate towards the SHAFT

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2
Q

where is the primary/ maximal site of bone growth?

A

hypertrophic zone within growth plate

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3
Q

what are the zones of the growth plate?

A
  1. germinal zone (closest to epiphysis)
  2. proliferative zone
  3. hypertrophic zone - area of maximal growth
  4. zone of endochondral ossification
  5. zone of Ranvier (closest to shaft/ diaphysis)
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4
Q

in the first year of life, what is the primary driver of growth?

A

thyroid hormone and GH-independent IGF-1, insulin

growth hormone becomes crucial after first year of life

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5
Q

what is the role of estrogens in growth plate maturation?

A

estrogens stimulate GH secretion and also promote growth plate “closure” (transition to bone)

this is why males tend to be taller, because there is more estrogen in females

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6
Q

what are 3 tools used to asses a child’s growth?

A
  1. growth charts/ velocity - is child growing at an appropriate rate for their age?
  2. midparental height - generates rough estimate of genetic height potential - is growth appropriate for their family?
  3. bone age of left hand/wrist - estimates pace of skeletal development - is growth appropriate for maturity?
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7
Q

what is the “rule of 5’s” of growth velocity in early development?

A

fetal: up to 100cm/year at peak
at birth: 50cm/year
0-1: 25cm/year
1-4: 10-15cm/year
4+: 5cm/year

growth velocity is most important physiologic metric for growth

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8
Q

what is “channeling down” growth variation?

A

benign variation in growth - most children change height percentiles in first 2 years of life as their own genetic potential becomes more influential than factors from their intrauterine environment (maternal and environmental factors)

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9
Q

what is “constitutional delay” of growth and puberty?

A

benign variation in growth - “late bloomers”

benign because they end up catching up

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10
Q

what is considered familial short stature?

A

benign variation in growth - less than 50th percentile, but growth is within expectations given family heights

initial birth length is often normal, but slows to low-normal growth velocity that is maintained throughout childhood

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11
Q

how is growth hormone deficiency measured/monitored, besides measuring hormonal levels?

A

growth failure after early infancy (6+ months old)

have low growth velocity for age, predicted adult height is below genetic potential (family), dropping height percentiles (2+)

however weight is preserved (normal or increased weight:height ratio)

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12
Q

Laron syndrome

A

defect in growth hormone receptor, causing growth hormone resistance

presents like GH deficiency, but with high or normal GH levels

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13
Q

what gene defect in Turner syndrome is responsible for causing short stature?

A

SHOX gene haploinsufficiency

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