Postnatal Growth

Question 1

What are the 3 phases of growth?

Answer 1

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 mainly dependent on sex steroids and increased GH release

Question 2

How do our proportions change as we grow?

Answer 2

We grow in a cephalo-caudal gradient,

Our legs grow faster than our post cranial body segments

Question 3

Mid parental height

Answer 3

Way to estimate how tall we will end up.
For a boy, mothers height + 13cm and average with fathers height.
For girl subtract 13cm from fathers height and average with mother

Important +- 8cm

Question 4

What is the HV?

can use bone age as a technique also?

Answer 4

The height velocity.
It differentiates a variant short stature from a pathological short stature.
Ideally is calculated over 6-12 months, and is normal between 25 and 75 centile
Tracks time

Question 5

Girls versus boys HV

Answer 5

Girls have a growth spurt (high HV) at on average around 2, and boys at 14.
All to do with oestrogen, oestrogen in girls earlier

Question 6

What is characteristic of normal variant short stature?

Determining between short stature or delayed growth?

Answer 6

Familial short stature or may have a delay of growth.
The hallmark is a normal height velocity!

CDGD has a delayed bone age, causing delayed puberty and ending up at normal height. Normal SS will just end up short

Question 7

How is growth hormone secreted?

Note that amount secreted decreases with age

Answer 7

In a pulsatile fashion, with a low baseline and primarily produced during sleep (3 and 4)

Increased by: Sleep, sex steroids, amino acids, malnutrition, exercise induced hypoglycaemia
Decreased by obesity and psychosocial deprivation

Question 8

What is the link between GH and nutrition?

Answer 8

Normal levels of insulin and nutrition needed for hepatic IGF-1 production
Malnutrition or poorly controlled diabetes can inhibit IGF-1 production. Also liver failure

Normal: GH induces liver to make IGF-1 which acts negatively on GH production

Poorly controlled diabetes, or liver problem will mean less circulating IGF-1, less negative feedback and increased GH

Question 9

Growth hormone actions

can act endorcine, paracrine or autocrine

Answer 9

– Inhibits glucose uptake and promotes
glycogenolysis (opposite to insulin)
– Stimulates protein synthesis.
– Promotes lipolysis

Question 10

IGF-1 features

note insulin required to make this, so diabetes in womb small skinnier babies (no fat storage)

Answer 10

• Major post natal growth promorting factor
• Made in liver and bone
• Insulin like effect of glucose, lipid and aa uptake to cause cell proliferation and differentiation

Question 11

Oestrogens role in growth

Answer 11

Effects skeleton and body composition, more so than testosterone
Responsible for epiphyseal maturation and closure

Question 12

Role in thyroid hormones in growth

Answer 12

Play a facilitatory role in growth
Necessary for GH production and growth plate development (body proportions too).

So hypothyroidism may cause short stature

Question 13

Differences in fetal vs child growth hormones

Answer 13

Fetus: IGF 2, insulin, PDGF. EFG, FGF
Child: GH, IGF1, T4/T3
Puberty: More of GH, E/T, T4/T3, Insulin, IGF-1

Question 14

IUGR

Answer 14

Usually do not reach MPH

Question 15

Turner syndrome

Answer 15

Short for MPH, only 50% present with SS
So SS, poor HV or delayed puberty.

Treat with GH