Endocrine Control of Growth

Question 1

Important factors during fetal growth

Answer 1

IGF-1 and IGF-2
Insulin
EGF and TGF-a
Little role for GH and no role of thyroid hormones

Question 2

Some determinants of post-natal growth

Answer 2

Nutrition/general health status
Psychosocial environment
Genetic factors
Absence of primary bone abnormalities
Hormonal factors

Question 3

Psychosocial dwarfism

Answer 3

Poor home environment and inadequate parenting
Abnormal GH secretion but GH treatment is not effective
Treatment: removal from environment and demonstration of catch-up growth

Question 4

Direct GH actions

Answer 4

Lipolysis
Increased amino acids transport into tissues
Increases protein synthesis in liver

Question 5

Sites of GH/IGF action

Answer 5

Epiphysis: stimulation of growth
Bone: stimulate osteoclast/blast activity, increase bone mass by endochondral bone formation
Adipose tissue: acute insulin-like effects followed by increased lipolysis
Muscle: increased AA transport, increased N retention, increased lean tissue

Question 6

Effects on blood sugar

1. GH
2. IGFs

Answer 6

1. Hyperglycemia

2. Hypoglycemia

Question 7

SRIF

Answer 7

Somatostatin

Hypothalamic peptide that inhibits pituitary release of GH

Question 8

Factors that promote GH release

Answer 8

Sleep
Stress
Exercise
Hypoglycemia
Arginine
Alpha-adrenergic agonists
Beta-adrenergic antagonists
Estrogens

Question 9

IGFBP-3

Answer 9

IGF Binding Protein
Coordinates GH and IGF1 actions
Regulates IGF1 delivery to the growth plate

Question 10

PIT-1

Answer 10

Transcription factor
Pituitary specific TF that is responsible for pituitary development and hormone expression
Results in hypoplasia of GH, PRL, and TSH secreting cells
Hard to test for, have to diagnose clinically

Question 11

GH Deficiency

Answer 11

Severe postnatal decrease in height velocity with tendency to truncal obesity
Hypoglycemia, micropenis, prolonged jaundice
High pitched voice, thin hair/skin
Delayed bone age and teeth eruption
Delayed puberty
Midline problems (cleft palate)

Question 12

2 major hormonal factors in growth

Answer 12

GH

TH

Question 13

Post natal hypothyroidism

Answer 13

Profound growth failure and virtual arrest of skeletal maturation
TH has a permissive effect on GH secretion so hypothyroidism will result in blunted GH response on provocative testing

Question 14

Signs and symptoms of hypothyroidism

Answer 14

Short stature +/- delayed puberty
Obesity
Low growth velocity
Decreased energy, increased sleep
Dry skin, constipation, cold intolerance
Developmental delay

Question 15

Signs of ACTH deficiency

Answer 15

Fatigue, weakness
GI complaints: vomiting, diarrhea, abdo pain
Circulatory collapse
Weight loss, growth retardation
Hypoglycemia

Question 16

Do you replace ACTH or TH first?

Answer 16

ACTH

Avoid precipitating an adrenal crisis

Question 17

What hormone causes the pubertal growth spurt?

Answer 17

Estrogens