Lecture 23: post-natal growth

Question 1

Abnormal growth can be caused from?

Answer 1

Genetic disorders

Endocrine disorders

Cartilage or bone disease

General chronic disease

Question 2

Phases of Growth?

Answer 2

Infant - rapid growth a birth declining over 2 years (less GH dependent)

Childhood - Constant anual growth (GH dependent)

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

Question 3

Mid-parental height?

Answer 3

An estimate to the height potential based on the parents heights

boys: (dad’s + (mum’s - 13cm))/2
girls: ((dad’s -13cm) + mum’s)/2

Useful height range and is +/- 8cm

Question 4

What is height velocity?

Answer 4

• HV differentiates normal variant short stature from pathological short stature
• Ideally calculated of 6-12 months and is calculted by dividing the height gain by the time interval between the two
• Normal HV lies between 25-75th percentile, the curve is shaped differently in children with delayed or early puberty.

Question 5

Short Stature?

Answer 5

• A common clinical presentation - a symptom or a variant and not a disease
• May indicate pathology BUT normal short stature still grow with normal HV
• Common manefestation of chronic illness

Question 6

Growth disorders?

Answer 6

Normal HV: Normal variants

• Familial short stature
• Constitutional delay in growth and development

Poor height velocity: Usually pathological

• Proportionate/disproportionate

Question 7

Bone Age?

Answer 7

Looks at the ‘age of the bones’ and used to predict adult height

Hand used (with lots of long bones) in X-ray looking at the formation of the bones - very hard to do.

Question 8

FSS vs CDGD

birthweight, chronic ilness, family Hx, infant growth, childhoodgrowth, late childhood growth, bone age, puberty and final height?

Answer 8

Puberty = ontime, delayed

Final height = short, normal

Question 9

Importance of:

ACTH, AVP, GH, TSH, Adrenal, Prolactin, Ocytocin, LH/FSH ?

Answer 9

ACTH: death

AVP: dehydrated

GH: severly short

TSH: short and slow

Adrenal: death

Prolactin: no food

Ocytocin: No labour

LH/FSH: No gonadal function

Question 10

Growth Hormone secretion? Nutrition and the GH axis?

Answer 10

Pulsatile with low baseline

Primarily at night time

Increased by: sleep, exercise, stress, hypoglycaemia, amino acids

Decreased by: obesity, psychosocial deprivation

GH causes the liver to make IGF-1 that then negatively inhibits GH release. In malnourished kids the liver doesn’t produce enough IGF-1

Question 11

GH actions?

Answer 11

Metabolic:

• inhibits glucose uptake and promotes glycogenolysis (anti-insulin)
• Stimuates protein synthesis
• Promotes lipolysis

ACTS: endocrine, paracrine, autocrine

• Bind to GH receptors on the perichondrocytes causeing IGF-1 release

Question 12

Role of IGF-1?

Answer 12

• Major post-natal growth promoting factor -(majority bound to binding proteins)
• Principally produced in the liver (endocrine) and bone (para, autocrine) acting on a wide range of tissues
• Insulin-like (promoting glucose, lipid and amino acid uptake) = cell proliferation and differentiation.

Question 13

Estrogen?

Answer 13

• Effects on skeleton and body composition (more so than testosterone on skeleton)
• responsible for epiphyseal maturation/closure in both sexes

Question 14

Thyroid hormones? Insulin?

Answer 14

T3 and T4 - facilitatory role in growth

necessary for normal GH secretion and growth plate development

Insulin - Facilitatory role in growth providing substrate for growth (aa uptake, glycogenesis and lipogenesis)

Question 15

GH at fetal, infant and child levels?

Answer 15

Fetal = IGF-1 and insulin

young children = GH, IGF-1, T3/4

Puberty = Inc. GH, IGF-1, E2/T, Insulin and same T3/4 levels

Question 16

Pathological short stature? categories?

Answer 16

Proportionate:

• IUGR
• syndromes
• Chronic ilness
• Psychosocial deprivation

Disproportionate:

• Syndromes (esp. turners)
• Hypothyroidism
• Skeletal dysplasia

Question 17

IUGR?

Answer 17

• Intrauterine growth retardation or SGA is very common with brth weight <10th PC
• Most have rapid catch up in 6 months byt 10% don’t
• Short stature by 2 years usually associated with short final height
• As a group these children do not reach MPHs

Question 18

Turner’s syndrome?

Answer 18

• Consider in all girls with unexplained short stature or height below MPH range - commonest feature
• 50% only have short stature as clinical feature and present with poor HV or delayed puberty
• May have: neck webbing, hand and foot oedema as infant, wide spaced nipples, increased carrying angle, cardiac abnormalities, renal/urinary tract abnormalities
• Karyotoype OX
• Elevated FSH and LH trying to initiate puberty