Growth Stats

Question 1

how do you measure bone growth, what life event is bone growth the best indicator of?

Answer 1

an x-ray of the (conventionally) left wrist shows the ossification pattern of the epiphyseal plate which reveals bone age;
it is the best indicator of puberty: 10-11 girls, 12 boys

Question 2

body compartment growth to adulthood?

Answer 2

muscle: 33 fold
bone: 23 fold
cardiac muscle: 19 fold
liver, kidney, skin: 10 fold
brain: 3 fold

Question 3

growth rates for childhood/puberty

Answer 3

prenatal: 130 cm/yr
0-6 months: 18-22 cm/yr (all cm/yr)
6-12 months: 14-18
second year: 11
third year: 8
puberty: 10-12 cm/yr

Question 4

what are the most critical steps in measuring growth?

Answer 4

accuracy and repetition

Question 5

what’s the difference between cross-sectional and longitudinal studies?

Answer 5

cross sectional will produce a smoother curve with more data points; longitudinal maybe more accurate but with a much more convoluted curve

Question 6

what are the equations for BMI?

Answer 6

English: Weight (lb)/height (in.) ^2 x 703
Metric weight (kg)/height (cm) ^2 x 10k

Question 7

which hormones cause advanced bone age?

Answer 7

TH, estrogen, androgens, corticosteroids

Question 8

the lack of which hormones cause retracted bone age?

Answer 8

GH, TH

Question 9

when is crossing percentiles common? when is it uncommon?

Answer 9

it’s common after birth until 3 years and then at puberty

it’s uncommon between 3 years and puberty

Question 10

what is birth height/weight a relevant indicator of?

Answer 10

health of the intrauterine environment

Question 11

how do you calculate (formula) mid-parental height?

Answer 11

((Father-5) + Mother)/2 : girls
((mother+5) + father)/2: boys
+/- 4 in.

Question 12

how much nutritional intake is devoted to growth?

Answer 12

2-13%

Question 13

what is the role played by hormones in growth?

Answer 13

catalysts, not activators

Question 14

IGF Facts: 
function
releasing hormone
biochemical length
serum level
half-life
method of circulation

Answer 14

anabolic hormone: uptake of amino acids by muscle to promote muscle growth
released by GH in liver
70 aa in length
serum levels are 100-1000 ng/ml
long half-life (days)
circulates bound to IGFBP3: IGFBP3 is responsible for its long half-life

Question 15

IGF has a high homology to what other common hormone? what’s the difference?

Answer 15

insulin; IGF maintains it “C” segment which is truncated when compared with insulin’s; it also has a short “D” segment attached to the “A” segment

Question 16

what effect do sex steroids have on growth? what does estrogen do?

Answer 16

sex steroids in general promote GH release, estrogen specifically promotes the closure of epiphyseal plates

Question 17

what is late bloomer syndrome

Answer 17

characteristic to men, don’t get pubertal growth spurt until early college years (10th % to 50th %); seems to be genetic

Question 18

what is familial short stature

Answer 18

genetic predisposition to just being in the 5th or slightly lower %, but steady throughout life, so no real disorder

Question 19

what two genes are transcription factors for the synthesis of GH (and TSH, prolactin)

Answer 19

PIT-1, PROP-1

Question 20

what TWO hypothalmic regulators influence the secretion of GH? what nuclei do they come from?

Answer 20

GHRH and somatsostatin; GHRH is arcuate nucleus and somatostatin is the PVN

Question 21

what percentage of the ant. pituitary is made up of somatotrophs?

Answer 21

50%

Question 22

when do you see the greatest spikes in GH levels? which sex has higher values?

Answer 22

during sleep - those on shift work have high peaks when they sleep, regardless of circadian clock; women;

Question 23

what hormone from the GI tract can cause the release of GH?

Answer 23

ghrelin

Question 24

what is the metabolic activity of GH?

Answer 24

it inhibits glucose metabolism and increases the breakdown of adipose tissue into FFA’s

Question 25

what are the intracellular mechanisms of GHR (once activated by GH)

Answer 25

via the JAK/STAT pathway